MEXICO CITY — Mexico's government vowed on Friday to find out whether an explosion that killed 33 people at the headquarters of its state-run oil monopoly Pemex was a deliberate attack or yet another stain on the company's safety record.

Rescue workers continued to pull bodies from the debris on Friday and officials said the search would continue until they account for everyone inside the Mexico City building.

Government officials have refused to speculate over what caused the explosion on Thursday but said they had deployed large teams of experts to pore through the wreckage.

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The government is determined to find out the truth, whatever that may be ... whether it was an accident, negligence or an attack, whatever," Attorney General Jesus Murillo said on Friday evening. "We are not going to rule out anything."

He said the explosion did not cause a fire but refused to be drawn on what that implied about the cause. Parts of the reinforced concrete ground floor of the building caved in, and the ceiling was a mess of twisted metal pipes and ducts.

The blast at Pemex's complex in the capital killed at least 33 people and a further 121 were injured. The scenes of chaos have dealt another blow to Pemex's image, just as Mexico's new government is seeking to open up the oil industry to more private investment.

Speculation over the cause has ranged from a bomb attack, to a gas leak, to a boiler blowing up.

"A fatal incident like yesterday's cannot be explained in two hours. We are working with the best teams in Mexico and from overseas. We will not speculate," Pemex's chief executive, Emilio Lozoya, said on Friday.

National mourning
New President Enrique Pena Nieto declared three days of national mourning.

Pemex, which was created when Mexico nationalized its oil industry in 1938, is a symbol of self-sufficiency but it has also been blighted by corruption, inefficiency and frequent accidents costing hundreds of lives.

The latest Pemex disaster is one of the first serious tests for Pena Nieto, who must overcome the legacy of his Institutional Revolutionary Party, or PRI, which ruled for much of the last century.

After seven decades in power, the party gained a reputation for corruption and cover-ups that have made Mexicans skeptical of whether they are being told the truth.

Investors have been closely following how far he will go in enticing private capital to boost flagging oil output in a country that is the world's seventh biggest producer.

"This incident speaks very poorly of the image of Pemex management, and that's interpreted as additional risk in the market,"said Miriam Grunstein, an energy researcher at Mexico's CIDE think tank.

A Pemex official said the damaged area of the company's headquarters was used for human resources in the corporate and refining divisions. It did not have a boiler or gas installations, the official said.

Former Pemex worker Ricardo Marin, 53, said there was nothing in the building that would explode and that the kitchen, where there would be gas, was on the other side.

"The only thing that occurs to me is that it was an attack — but against whom? There's no one with an important job down there," he said, waiting outside the Pemex hospital where a friend was in intensive care. "Maybe it could be a message to Pena Nieto, but not even that has any logic."

Pemex office worker Alfonso Caballero, who was one floor above the blast at the time, said he did not smell any gas and guessed it had been caused by machinery.

Mexican officials have not ruled out sabotage.

An official at the U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives said an "international response team" was on its way to Mexico City at the request of the Mexican government. The team includes explosive specialists and fire experts.

Pemex CEO Lozoya said the four floors most affected by the explosion normally had about 200 to 250 people working on them.

About 10,000 staff work in the entire complex.

Red Cross official Isaac Oxenhaut said the ceiling had collapsed in three lower floors of the Pemex building.

Safety in the spotlight
The blast followed a September fire at a Pemex gas facility near the northern city of Reynosa that killed 30 people. More than 300 were killed when a Pemex natural gas plant on the outskirts of Mexico City blew up in 1984.

Eight years later, about 200 people were killed and 1,500 injured after a series of underground gas explosions in Guadalajara, Mexico's second-biggest city. An official investigation found Pemex was partly to blame.

Whatever caused the explosion, the deaths and destruction will put the spotlight back on safety at Pemex, which only a couple of hours beforehand had issued a statement on Twitter saying it had managed to improve its record on accidents.

"I suspect this was a bomb," said David Shields, an independent Mexico City-based oil analyst. "There are clandestine armies across Mexico, not just the (drug) cartels."

Shields pointed to the bombing of several Pemex pipelines in the eastern state of Veracruz in 2007. A shadowy Marxist rebel movement took credit for some of the blasts.

Meanwhile, George Baker, director of Energia.com, a Houston-based energy research center, said past history suggested the government could seek to exploit the incident.

He pointed to the 1992 Guadalajara blast and the subsequent deal that followed to overhaul the Pemex administration led by then-President Carlos Salinas, like Pena Nieto a PRI member.

"Salinas said he wanted a response from Pemex, and months later Pemex announced a restructuring. The restructuring had nothing to do with the Guadalajara accident, but it was used as a pivot to do something," Baker said.

Pena Nieto has yet to reveal details of his Pemex reform plan, which already faces opposition from the left.

Both Pena Nieto and his finance minister were this week at pains to stress the company will not be privatized.

Related:

At least 33 dead in Mexico City skyscraper explosion

A suicide bomber blew himself up at an entrance to the U.S. Embassy compound in Ankara, Turkey, on Friday, officials said.

U.S. State Department and Turkish interior ministry officials said the bomber and a Turkish guard were killed in the attack, which took place about 1:15 p.m. local time (6:15 a.m. ET).

"Clearly, it’s a terrorist attack," State Department spokeswoman Victoria Nuland said in a media briefing, adding that the U.S. condemns the hit in strong terms.

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The bomber, who was wearing a suicide vest, made it to the first X-ray machine in a screening area leading to the visa section, police sources said, and then detonated the device.

The Turkish security guard standing nearby was killed, but two guards on the other side of the checkpoint, behind bulletproof glass, survived. In the immediate aftermath of the attack, sources had said three people were thought to have been killed.

Prime Minister Tayyip Erdogan said the bomber was a member of the Revolutionary People's Liberation Party-Front, or DHKPC, a far-left group designated a terrorist organization by the United States and the European Union.

That group, started in the late 1970s, "has periodically targeted both Turkish officials and been virulently anti-U.S. and anti-NATO during the Gulf War and continuing to today," Michael Leiter, former director of the U.S. National Counterterrorism Center, said in an interview with NBC News.

"During the past several months Turkish officials have targeted the DHKPC and it is possible that this was in retaliation for those police raids," he said, adding that the group's reach was believed to be limited to Turkey and the immediate region.

There was, however, no claim of responsibility.

Nuland said a Turkish citizen was hurt and is in "serious condition." Reuters reported this victim was Didem Tuncay, a journalist on her way in to the embassy to meet U.S. Ambassador Francis Ricciardone. Several U.S. and Turkish staff members were hit by flying debris and treated at the scene.

"We're very sad of course that we lost one of our Turkish guards at the gate," Ricciardone said, according to Reuters, thanking Turkish authorities for their response.

Turkish television footage taken shortly after the attack showed smoke rising from the area and a heavily damaged door that led to a side street.

Turkish media reports identified the bomber as Ecevit Sanli. Reuters said Sanli was previously involved in attacks on a police station and a military staff college in Istanbul in 1997.

Nuland said the attack happened on an external perimeter access site whose level of security protection ensured that the strike wasn't worse.

The White House said Friday it was not yet clear who was responsible for the bombing.

"The attack itself was clearly an act of terror," Jay Carney, White House spokesman, said in a briefing with reporters.

The State Department said the U.S. will cooperate with the Turkish side on the investigation into the attack.

Erdogan, who was attending a ceremony in Istanbul when the blast happened, said the attack "shows that we need to fight together everywhere in the world against these terrorist elements." 

In an emergency message Friday, the State Department said Americans were "advised to not visit the Consulates in Istanbul, Adana or the Embassy in Ankara until further notice."

"The Department of State advises U.S. citizens traveling or residing in Turkey to be alert to the potential for violence, to avoid those areas where disturbances have occurred, and to avoid demonstrations and large gatherings," the message said.

In Berlin on Friday, Vice President Joe Biden said that he appreciated an "expression of sympathy" over the attack from German Chancellor Angela Merkel, saying it reinforced the "very close counterterrorism cooperation that exists between Germany and the United States."

On Sept. 11 last year, U.S. Ambassador Christopher Stevens and three other Americans were killed in an attack on the U.S. Consulate in Benghazi, Libya, prompting concern about security for diplomats.

On Jan. 23, Secretary of State Hillary Clinton told the Senate Foreign Relations Committee that she took responsibility for not adequately protecting U.S. personnel in Benghazi. Her voice choked with emotion as she remembered the return of "flag-draped caskets" and putting her arms around relatives of those who died. 

Nuland said on Friday that after Benghazi, every U.S. post in the world reviewed its security. She added that the embassy in Ankara is one of the posts due for a complete compound overhaul. The building housing the embassy was built in the 1950s and needs a full upgrade, Nuland said.

Homegrown Islamic militants tied to al-Qaida have carried out suicide bombings in Istanbul, killing 58, in 2003. The targets were the British consulate, a British bank and two synagogues. 

In 2008, an attack blamed on al-Qaida-affiliated militants outside the U.S. Consulate in Istanbul left three assailants and three policemen dead. 

In the November 2003 attack on the British consulate, a suspected Islamic militant rammed an explosive-laden pickup truck into the main gate, killing British Consul-General, Roger Short, and his assistant, Lisa Hallworth. 

The State Department says on its website that 15 people who claimed they were associated with al-Qaida were arrested in July 2011 for gathering explosive materials in preparation for an attack on the U.S. Embassy in Ankara. 

It added that the July plot and other incidents "show a willingness on the part of some terrorist groups to attack identifiably Western targets. The possibility of terrorist attacks, from both transnational and indigenous groups, remains high."

The State Department says the PKK Kurdish rebel group is the "most active terrorist organization in Turkey." It said the PKK had historically targeted Turkish government and military interests, but had recently "threatened increased violent activity in Turkey’s urban areas, and there is credible information suggesting that it intends to continue targeting tourist areas as well."

Earlier this month, about 400 U.S. personnel arrived at Turkey’s Incirlik Air Base to support the deployment of a NATO Patriot missile battery to help defend the country from possible incursions by Syria’s forces during that country’s ongoing civil war.

Reuters, The Associated Press and NBC News Staff Writers Kari Huus, Alastair Jamieson and Becky Bratu contributed to this report.

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The death toll from a powerful explosion in the Mexico City skyscraper complex housing the offices of state oil monopoly Pemex rose to at least 33, company and government officials said Friday.

Twenty men and 12 women were killed, the company said — while 121 were injured, 52 of whom remain in hospital. 

Mexican President Enrique Peña Nieto arrived at the Pemex administration complex by helicopter Thursday night to supervise rescue operations, Pemex and the news agency La Prensa reported. Hundreds of Mexican military forces were sent to the complex to "preserve security," officials told newspaper El Universal.

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Rescue crews had searched most of the area damaged by the blast by Friday afternoon, said Attorney General Jesus Murillo said. But he added that survivors or more victims could still be found in the most unstable parts, which had not yet been fully checked.

Emilio Lozoya Austin, director general of Pemex, which is short for Petrõleos Mexicanos, told Reuters Friday the the company was "working with the best teams in Mexico and from overseas" to find the cause of the explosion.

He was flying home from a business trip to Asia when the blast occured. He said he extended his condolences "to all the families of Pemex workers who have lost their loved ones."

The explosion took place in the basement garage of the auxiliary building, next to the company's 52-floor tower in a busy commercial and residential area, said Eduardo Sánchez, a spokesman for the Interior Ministry.

"They're conducting a tour of the building and the area adjacent to the blast site to verify if there are any still trapped so they can be rescued immediately," Sanchez said Thursday.

A government official, speaking on the condition of anonymity, said preliminary findings suggested the blast was caused by aged boiler exploding in a building next to the tower, Reuters reported.

The plaster ceiling of the basement collapsed, a spokesman for the local emergency agency said. He described conditions in the tower as "delicate."

The main floor and the mezzanine of the auxiliary building were heavily damaged, along with windows as far as three floors up. 

A man who was on the ground floor when the explosion occurred told Forum TV that the first casualties were taken to a clinic in the adjacent office tower, where several thousand people work.

"It shook the building, and then we were evacuated," he said.

Company touted safety record
News of the blast came toward the end of the business day — just a few hours after the company had sent two messages on Twitter celebrating how much it had "reduced our accident rate in recent years," announcing that its "safety indicators" exceeded international standards:

"An explosion took place in the B2 building of the administrative center," Pemex tweeted just after 4 p.m. local time (5 p.m. ET). "There are injuries and damage on the ground floor and mezzanine," it said, promising further information as it became available.

Pemex initially said the building had been evacuated because of a problem with its electricity supply. It then said there had been an explosion, but it didn't give the cause.

Television images showed people being evacuated — some on office chairs and gurneys. Emergency crews loaded people on stretchers into helicopters and airlifted them out of the area.

"The place shook, we lost power and suddenly there was debris everywhere," Cristian Obele told Milenio news network. "Colleagues were helping us out of the building."

Jose Cuellar, a mechanic who works near the complex, said he was repairing a car when an explosion rocked his entire workshop.

"We went to see and saw people coming out injured," Cuella, 45,  told El Universal. "Other people were carrying them."

Edgar Zuniga Jr. and M. Alex Johnson of NBC News, Telemundo and Reuters contributed to this report.

A truck carrying fireworks ahead of Chinese New Year celebrations exploded and destroyed part of an elevated highway in China's Henan Province, killing several people, state media reported.

The blast sent vehicles plummeting 100 feet to the ground, state media said.

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A 260-foot section of road was damaged, the BBC reported.

China National Radio said 26 people were killed, while the Xinhua News Agency reported only four deaths but said search and rescue efforts were continuing, The Associated Press reported.

The explosion happened early Friday on a major east-west highway in Mianchi county, about 55 miles west of Luoyang, the AP said.

Pictures from state broadcaster CCTV showed rescuers digging through rubble in the aftermath of the accident.

In 2006, a storeroom of fireworks exploded at a temple fair in Henan, killing 36 people and injuring dozens more, the Daily Telegraph said.

 

 

BAGHDAD — Bombings on Shiite neighborhoods in Baghdad and a blast on an Iranian pilgrim bus killed more than 30 people on Saturday, marring Iraqi celebrations of the second day of the Islamic Eid al Adha religious festival.

Violence in Iraq has eased sharply, but Sunni Islamist insurgents and al-Qaida's Iraq wing often target Shiites in an attempt to stir up the kind of sectarian tensions that dragged the country close to civil war in 2006-2007.

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Two car bombs exploded on Saturday, one ripping into a restaurant in the Shiite stronghold of Sadr City and killing at least 23 people, police and hospital sources said.

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"I was just selling fruit and we were surprised by a huge explosion on the other side of the street," Hassan Falih Shami, a grocery stall owner near the site of the blast. "You can see pools of blood, the shoes and pieces of clothing."

Hours earlier, a roadside bomb planted near an open-air market killed seven people, including three children at a playground. Another blast killed six people when it hit a bus carrying Iranian pilgrims to a Baghdad shrine, police and hospital officials said.

Police said the attack on the Iranian pilgrims came from a bomb that had been attached to their bus. It exploded around 300 yards from a police checkpoint, sending the bus out of control before it flipped over on its side.

Insurgents have carried out at least one major attack a month since the last U.S. troops left in December. Iraqi officials worry Syria's crisis is bolstering Iraqi insurgents.

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The monthly death toll from attacks in Iraq doubled in September to 365, the highest number of casualties in two years, including a series of bombings targeting Shiite neighborhoods that killed more than 100 people.

Security officials had said they believe insurgents would try to carry out a large attack during the religious holiday, which started on Friday.

Car bombs exploded and mortars landed around the Shiite neighborhood of Shula, northwestern Baghdad, on Tuesday killing eight people and wounding 28, and another person was killed by a mortar round in Kadhimiya area.

Reporting by Raheem Salman; Writing by Patrick Markey

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OSAKA — Explosions at a chemical plant in Hyogo Prefecture on Saturday killed a firefighter and injured dozens of people, the Japan Times reported, citing local fire department and police officials said. Global production of diapers could be affected because the plant made a key ingredient in a resin used in them, Japanese media reported.

 

A fire broke out about 2 p.m. after an abnormal chemical reaction at Nippon Shokubai Co.'s plant in Himeji, the Japan Times said.

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The first explosion occurred about 2:40 p.m. as firefighters were spraying an acrylic acid tank with water, and the second followed shortly afterward, the Times said, citing Nippon Shokubai. The blasts set ablaze a fire engine.

A 28-year-old firefighter was killed and at least 30 people were reported injured.

Nippon Shokubai is one of the world's biggest makers of acrylic acid, the main ingredient of a resin called SAP, which is used in diapers.

The plant produces about 20 percent of the world's SAP and 10 percent of global output of acrylic acid.

Operations at the plant are likely to be halted for a long time and other makers of SAP resins are operating on a full-production footing, leaving little room for back-up production, the Nikkei business daily said on Sunday.

This article includes reporting from NBC News staff and Reuters.

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A suicide bomber detonated explosives near the heavily barricaded NATO headquarters in Kabul on Saturday, killing six civilians, NATO and local officials said.

The bomber, who was riding an explosives-laden motorcycle, blew himself up near the entrance of Camp Eggers, a NATO spokeswoman said, referring to a sprawling base that is home to 2,500 coalition personnel who train Afghan security forces.

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The blast was the latest example of how militants are able to strike the heart of the Afghan capital even after more than a decade of fighting Western forces with far superior firepower. It also raises questions about Afghan forces' ability to combat insurgents once most foreign troops leave by the end of 2014.

Pieces of flesh and splattered blood lay on the street near the base, where small bodies were seen being lifted into ambulances, witnesses said.

Young children were among the dead, said Ministry of Interior spokesman Sediq Sediqqi.

The Afghan Interior Ministry said five people were wounded in addition to the six deaths, The Associated Press reported.

Jamie Graybeal, a spokesman for the U.S.-led international military alliance, told The AP that all coalition compounds in Kabul were currently secure. He said he was not aware of any casualties among members of the coalition.

Taliban claims responsibility
The Taliban took responsibility for the attack, saying they had despatched a bomber to target the Kabul offices of the U.S. Central Intelligence Agency (CIA).

"One of our mujahideen targeted an important intelligence office used for recruiting Americans and Afghans for spying," Taliban spokesman Zabihullah Mujahid told Reuters.

Haqqani network: Terrorist designation adds to captured GI's 'woes'

Sediqqi speculated on his Twitter feed that Saturday's attack, just before noon, may have been carried out by the Haqqanis, the most experienced insurgents in Afghanistan.

On Friday the United States said it is designating the Haqqani network -- blamed for a number of high-profile attacks on Western and Afghan targets in Kabul -- a terrorist organization.

'I'm myself again': Photographer Giles Duley returns to work after Afghanistan blast

Senior Haqqani commanders told Reuters from an undisclosed location that the move showed the United States was not sincere about peace efforts in Afghanistan and warned of more attacks on American forces in Afghanistan.

The bombing on Saturday happened as celebrations were underway in Kabul to commemorate the 11th anniversary of the death of Ahmad Shah Massoud, the hero of the 1980s war against Soviet occupiers, and later of opposition to the Taliban.

Massoud was killed on September 9 by al Qaeda militants posing as reporters.

Reuters and The Associated Press contributed to this report.

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Updated at 10:10 p.m. ET: A huge explosion rocked Venezuela's biggest oil refinery and unleashed a ferocious fire on Saturday, killing at least 39 people and injuring more than 80 others in one of the deadliest disasters ever to hit the country's key oil industry.

Balls of fire rose over the Amuay refinery, among the largest in the world, in video posted on the Internet by people who were nearby at the time. Government officials pledged to restart the refinery within two days and said the country has plenty of fuel supplies on hand to meet domestic needs as well as its export commitments.

The explosion shattered walls of nearby shops, ripped out windows from homes and left the surrounding streets covered with rubble and twisted scraps of metal.

President Hugo Chavez declared three days of mourning and ordered an investigation to determine the cause of the explosion. "This affects all of us," Chavez said by phone on state television. "It's very sad, very painful."

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Vice President Elias Jaua, who traveled to the area in western Venezuela, said on state television late Saturday that at least 39 people were killed by the explosion, up from the earlier death toll of 26. He said that the dead included 18 National Guard troops and that six of the bodies had not yet been identified. Other officials said earlier that the dead included a 10-year-old boy.

In a neighborhood next to the refinery, shopkeeper Yolimar Romero said she was at her computer when a shock wave swept over the area shortly after 1 a.m.

"At that instant, the whole house shook as if it were an earthquake," she said. "The windows went flying off with their frames and everything."

Electricity was knocked out, leaving Romero in the dark and her house filled with smoke. She found a flashlight and started looking for her husband and three children.

Outside on the street, the family saw scattered hunks of brick walls and ruins of a National Guard post and about 20 other homes. Bodies were being pulled from buildings down the street.

At least 86 people were injured, nine of them seriously, Health Minister Eugenia Sader said at a hospital where the wounded were taken. She said 77 people suffered light injuries and were released.

Officials said firefighters had largely controlled the fire at the refinery on the Paraguana Peninsula, where flames were still visible on Saturday night after billowing dark smoke all day.

The blast occurred about 1:15 a.m. when a natural gas leak created a cloud that ignited, Oil Minister Rafael Ramirez said.

"That gas generated a cloud that later exploded and has caused fires in at least two tanks of the refinery and surrounding areas," Ramirez said.

Images shortly after the explosion showed the flames casting an orange glow against the night sky, and injured survivors on a stretcher and in a wheelchair. The bloodied bodies of victims were loaded onto pickup trucks.

Ramirez said a panel of investigators was being formed to determine the cause of the gas leak. A prosecutor was appointed to lead the investigation and troops were deployed to the area.

While the cause of the disaster remains unclear, some oil workers and critics of Chavez's government have recently pointed to increasing numbers of smaller accidents and spills as an indication of problems within the state-run company.

"We warned that something was going to happen, a catastrophic event," said Ivan Freites, secretary general of a 1,200-member union of oil and natural gas industry workers in Falcon state where the refinery is located. He spoke in a telephone interview from an area near the refinery, where he could see the flames raging in the distance.

The refinery complex's general manager, Jesus Luongo, denied that a lack of maintenance was to blame, saying in the past three years more than $6 billion has been invested in maintaining the country's refineries.

Ramirez said the explosion hit an area of storage tanks, damaging nine tanks.

"All of the events happened very quickly," Ramirez said. "When we got here in the middle of the night, at 3 or 3:30 in the morning, the fire was at its peak."

The oil minister said that supplies of fuel had been cut off to part of the refinery and that firefighters were using foam to extinguish the flames in one of the remaining tanks.

"This regrettable and sad event is controlled, is under control," Ramirez said on television, while plumes of smoke continued to billow.

Amuay is part of the Paraguana Refinery Complex, which also includes the adjacent Cardon refinery. Together, the two refineries process about 900,000 barrels of crude per day and 200,000 barrels of gasoline. Venezuela is a major supplier of oil to the U.S. and a member of the Organization of Petroleum Exporting Countries.

Ramirez said the state oil company Petroleos de Venezuela SA should be able to "restart operations in a maximum of two days."

"We want to tell the country that we have sufficient inventories of fuel. We have 10 days of inventory of fuel," Ramirez said. He said the country's other refineries were operating at full capacity and would be able to "deal with any situation in our domestic market."

An official of the state oil company, known as PDVSA, said the country also has enough supplies on hand to guarantee its international supply commitments. The official spoke on condition of anonymity because he wasn't authorized to speak publicly about the matter.

In terms of international oil markets, the disaster is not likely to cause much of a ripple, said Jason Schenker, an energy analyst and president of Austin, Texas-based Prestige Economics LLC. Noting that other refinery accidents and shutdowns regularly occur around the world, he said: "There's likely to be relatively limited impact on global crude or product pricing."

"The real tragedy," he said, "is that these events continue to happen, not just in Venezuela but everywhere. It is a dangerous business."

Gustavo Coronel, an energy consultant and former PDVSA executive, called the tragedy "probably the worst one the oil industry has had in many years."

"Accidents happen, of course, although the problem with PDVSA is the inordinate amount of accidents that have taken place during the last years," Coronel said. Considering the overall record, "we are not talking about bad luck but about lack of maintenance and inept management," he said.

The labor leader Freites, who has worked at the refinery for 29 years, said workers had repeatedly alerted state oil company officials to problems that they feared could lead to an accident. "We've been complaining about problems and risks, including fires, broken pipes and a lack of spare parts," Freites said.

One opposition group comprised of former PDVSA employees, Gente del Petroleo, or Oil People, said it could not yet pass judgment on the cause of the explosion. But it but noted there had been ample concerns about lack of maintenance and poor management.

The group said in a statement that since 2003, 79 other serious accidents have been reported at the Paraguana Refinery Complex, collectively killing a total of 19 workers and injuring 67 others.

Opposition leader Henrique Capriles, who is challenging Chavez in the country's Oct. 7 presidential election, expressed condolences to the victims and their families.

"We Venezuelans are one, and we grow in the face of this type of situations," Capriles said.

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A suicide bomber who blew up a bus in Bulgaria last week, killing five Israeli tourists, was backed by an organized group who helped him plan and carry out the attack, Bulgarian Prime Minister Boiko Borisov said on Tuesday.

Borisov said police had not yet identified the bomber, who along with the Bulgarian bus driver also died. More than 30 people were wounded in Wednesday's attack at Burgas airport.

Borisov said the perpetrator had not acted alone.

"These are extremely experienced people who have followed strict conspiracy rules," Borisov told reporters after meeting John Brennan, a U.S. counter-terrorism adviser to President Barack Obama.

"From what we see, they arrived nearly a month beforehand, changed rental cars, and traveled to different cities ... and not more than one of the people we are looking for was captured on either security camera," Borisov said.

He declined to give more details on the plotters.

"There was absolutely no chance of preventing such an act of violence," Borisov insisted, according to The Associated Press. "We could have only detected it by chance or if we had been informed by the services that such activities were under way in Bulgaria."

 

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Borisov said that the bomber's DNA and fingerprints had not matched anything held on file by Bulgaria or by partner spy agencies.

Bulgaria official: Suspected suicide bomber carried fake Michigan license

He suggested that the attacker, whose bomb was concealed in his backpack, may have entered Bulgaria on a plane from the European Union's "Schengen" passport-free travel zone.

"We do not know his identity, but it is known when he has arrived, the presumed flight, where he came from. It could turn out that he entered Bulgaria from a Schengen member country," Borisov said.

Israel's military chief insisted Tuesday that Iran and Hezbollah were involved and vowed that Israel would respond to the attack.

"We will have to find a way to respond to this attack, and not just a one-off," Lt. Gen. Benny Gantz was quoted as telling the Israeli parliament's foreign affairs and defense committee. "We will know how to do it judiciously. Ultimately, the response will come."

His comments were relayed by a meeting participant who discussed contents from the closed session on condition of anonymity. Iran has denied the accusations.

Borisov said that Bulgaria -- a member of both the European Union and NATO -- would not say who it thought was responsible for the attack until the investigation was complete.

Brennan said the U.S. has been working with Bulgaria on the investigation.

"Bulgaria will continue to have the full support of the United States in the weeks and months ahead," Brennan said.

Reuters and The Associated Press contributed to this report.

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DIYARBAKIR, Turkey -- An explosion and fire has shut down twin pipelines that carry oil from Iraq to the Mediterranean, an official said Saturday. No one was hurt in the blast.

The explosion late Friday hit a section of a pipeline that carries oil from the northern Iraqi city of Kirkuk to the Turkish port of Ceyhan, near the southeastern town of Midyat, Energy Ministry official said. A second line that runs parallel was not damaged, but was also shut down as a precaution, the official said.

The official, who spoke on condition of anonymity because of government rules, said the cause of the blast was under investigation but was most likely the result of sabotage.

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The explosion started a fire at 11 p.m. (5 p.m. ET) on Friday, security sources said. Firefighters were battling to put out the blaze.

Officials blamed the attack on the Kurdistan Workers Party (PKK), a Kurdish separatist group that has claimed responsibility for past attacks on the 600-mile pipeline.

Firat News, a website with ties to the PKK, also said the outlawed group was behind the attack.

Insurgents in Iraq have disrupted the transport of oil on the Kirkuk-Ceyhan pipeline, the country's largest, in the past, and technical faults on the 35-year-old link, which consists of two pipes, have also cut flows.

The PKK, designated a terrorist group by Turkey, the United States and the European Union, took up arms against the Turkish state in 1984, and more than 40,000 people, mainly Kurds, have died in the conflict. It has claimed responsibility for attacks on other natural-gas and oil pipelines in what it has said is a campaign to target Turkey's strategic assets.

It was not clear when oil flows to Ceyhan would resume.

Reuters and The Associated Press contributed to this report.

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Updated at 6:04 p.m. ET: SOFIA, Bulgaria -- An explosion on a bus carrying Israeli tourists at an airport in Burgas killed at least six people and injured 32 others, Bulgarian authorities said. Bulgarian officials could not confirm the deadly blast was terror-related but Israeli Prime Minister Benjamin Netanyahu blamed Iran.

"Iran is responsible for the terror attack in Bulgaria, we will have a strong response against Iranian terror," said Netanyahu in a statement, according to Haaretz, an Israeli newspaper.

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Tehran did not immediately issue a comment.

A bomb caused the explosion, Bulgarian Foreign Minister Nikolai Mladenov told Reuters.

The Israelis had landed at the airport around 4:45 p.m. local time (9:45 a.m. ET) and boarded a bus to their hotel when the explosion happened, The Jerusalem Post reported. Body parts were flung onto the tarmac and a thick black plume of smoke rose above the airport.

An 11-year-old Israeli girl and two pregnant women were among those injured, according to Focus, a Bulgarian news agency.

"I do not know what it was, but it was a very powerful blast, and I think it was something placed on purpose in the bus, which carried 47 Israeli tourists," Burgas mayor Dimitar Nikolov told BTV television. Burgas is 250 miles from Sofia, Bulgaria's capital.

Nikolov said 171 people had arrived on a plane from Israel to spend their holiday at the Black Sea coast. One American and one Slovenian passenger were on board, he said.

The Bulgarian Press Office, which provided the casualty figures, said only one bus was involved in the explosion, but added the investigation is ongoing. 

According to a Bulgarian news service, an eyewitness named Daniel told the Voice of Israel radio program: “I was literally watching people crawling out of the bus. They were screaming and one of them had no arms or legs. It was horrible.”

Another Israeli traveler told the radio station: “The people who survived got through the windows and were trying to crawl over the bodies. The bus was destroyed from both sides.”

In separate statements, President Barack Obama, Secretary of State Hillary Clinton and United Nations Secretary-General Ban Ki-moon condemned the attack.

"As Israel has tragically once more been a target of terrorism, the United States reaffirms our unshakeable commitment to Israel's security, and our deep friendship and solidarity with the Israeli people," Obama said. He called Netanyahu on Wednesday to express his condolences.

Clinton said the U.S. is prepared to offer "any assistance necessary" and that she was prepared to "work with our partners in Bulgaria, Israel and elsewhere so that the perpetrators can be apprehended swiftly and brought to justice for this appalling crime."

Wednesday's bombing coincided with the 18th anniversary of the bombing of a Jewish community center in Argentina that killed 85 people. According to the BBC, Argentinian prosecutors charged Iran with orchestrating the attack, which they believe was carried out by Hezbollah, the Lebanon-based militia. 

Netanyahu said Israel would respond.

"All the signs lead to Iran. Only in the past few months we have seen Iranian attempts to attack Israelis in Thailand, India, Georgia, Kenya, Cyprus and other places," Netanyahu said in a statement. "This is an Iranian terror attack that is spreading throughout the entire world. Israel will react powerfully against Iranian terror."

But Jerusalem Post writer Yaakov Katz questioned the connection between the two events.  

"While the attack is severe, it is not of the scale of what happened in 1994," Katz wrote. In 1994 in Argentina, a van filled with explosives rammed into the Jewish community center, killing 84 people. Wednesday's attack, he said, appeared to have been perpetrated by a suicide bomber or a planted bomb. 

"This is a break from Hezbollah's traditional tactic of carrying out attacks with less of a footprint," Katz wrote. "In previous plots that were thwarted recently, there were attempts to shoot down Israeli airliners with shoulder-to-air missiles, to plant bombs on diplomatic cars or to assassinate Israeli diplomats. Nothing that would leave evidence behind."

Israeli officials had previously said that Bulgaria, a popular holiday destination for young Israeli tourists, was vulnerable to attack by Islamist militants who could infiltrate via nearby Turkey.

Israeli diplomats have been targeted in several countries in recent months by bombers who Israel said struck on behalf of Iran.

Though Tehran has denied involvement, some analysts believe it is trying to avenge the assassinations of several scientists from its controversial nuclear program, which the Iranians have blamed on Israel and its Western allies.

Israel has threatened air strikes against Iran's nuclear facilities if diplomatic efforts fail to stop Tehran getting nuclear weapons, which it denies it is seeking.

The Israel Airports Authority announced disruptions in flights from Israel and Europe, according to Haaretz.

NBC's Lawahez Jabari in Jerusalem, Reuters and The Associated Press contributed to this report.

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