Musa Farman / EPA

Smoke billows from the scene of a bomb blast in Kirani road area of Quetta, the provincial capital of restive Balochistan province, Pakistan, 16 Febuary 2013.

Dozens of people including school children were killed Saturday in a bomb attack carried out by extremists from Pakistan's Sunni Muslim majority, police said.

A spokesman for Lashkar-e-Jhangvi, a Sunni group, claimed responsibility for the bomb, which caused casualties in Quetta's main bazaar, a school and a computer center. Police said most of the victims were Shiites.

Burned school bags and books were strewn around.

Early Sunday, a Pakistani police official said that the blast killed 81 people, with many of the critically injured dying overnight, The Associated Press reported.

"The explosion was caused by an improvised explosive device fitted to a motorcycle," said Wazir Khan Nasir, deputy inspector general of police in Quetta.

"This is a continuation of terrorism against Shiites."

"I saw many bodies of women and children," said an eyewitness at a hospital. "At least a dozen people were burned to death by the blast."

Most Western intelligence agencies have regarded the Pakistani Taliban and al Qaeda as the gravest threat to nuclear-armed Pakistan, a strategic U.S. ally.

But Pakistani law enforcement officials say Lashkar-e-Jhangvi has become a formidable force.

Tensions

Banaras Khan / AFP - Getty Images

Pakistani paramedics work over the dead bodies of bomb blast victims at a hospital in Quetta on February 16, 2013. A remote-controlled bomb targeting Shiite Muslims killed 47 people including women and children and wounded more than 200 in Pakistan's insurgency-hit southwest on Saturday, police and officials said. AFP PHOTO/Banaras KHANBANARAS KHAN/AFP/Getty Images

Last month the group said it carried out a bombing in Quetta that killed nearly 100 people, one of Pakistan's worst sectarian attacks. Thousands of Shi'ites protested in several cities after that attack.

Pakistani intelligence officials say extremist groups, led by Lashkar-e-Jhangvi, have escalated their bombings and shootings of Shiites to trigger violence that would pave the way for a Sunni theocracy in U.S.-allied Pakistan.

More than 400 Shiites were killed in Pakistan last year, many by hitmen or bombs, and the perpetrators are almost never caught. Some hardline Shi'ite groups have hit back by killing Sunni clerics.

The growing sectarian violence has hurt the credibility of the government, which has already faced criticism ahead of elections due in May for its inability to tackle corruption and economic stagnation.

The schism between Sunnis and Shiites developed after the Prophet Muhammad died in 632 when his followers could not agree on a successor.

Emotions over the issue are highly potent even today, pushing some countries, including Iraq five years ago, to the brink of civil war.

Pakistan is nowhere near that stage but officials worry that Sunni extremist groups have succeeded in dramatically ratcheting up tensions and provoking revenge attacks in their bid to destabilize the country.

Attackers threw a homemade bomb at an administration building belonging to the Egyptian Coptic church in Dafniya, close to the western city of Misrata, said Ibrahim Rajab of the Misrata military council.

The Egyptian consul in the city, Tareq Dahrouj, said he visited the church and the building where the two church workers were killed early on Sunday.

"The explosion seems like it was very strong and I have started making my investigations with Misrata officials,'' he said.Libya has small communities of Egyptians, Greeks and Italians who account for most of the Christian minority in the predominantly Islamic country.

Libya's new rulers have struggled to impose their authority on myriad armed groups who helped oust dictator Moammar Gadhafi last year but have yet to lay down their arms. Sunday's attack was the first major assault on a Christian target since the revolution.

Coptic Christians in Egypt have become increasingly worried after an upsurge in attacks on churches, which they blame on hardline Islamists, in the wake of the removal from office in 2011 of President Hosni Mubarak.

Repeated attacks on foreign diplomatic and aid centers in Libya's eastern city of Benghazi have made it very dangerous for non-locals to work and live there.

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The worst attack on a foreign target was on Sept. 11, when the U.S. Ambassador Chris Stevens and three embassy staff were killed in an attack on the U.S. mission in Benghazi.

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T. Mughal / EPA

People react at the site of a suicide bomb attack targeting a Shiite Muslim mourning procession in Rawalpindi, Pakistan, Wednesday.

Updated at 7:29 a.m. ET: A Taliban suicide bomber struck a procession near Pakistan's capital, killing 23 people in the latest of a series of bombings targeting Shiite Muslims during the sect's holiest month of the year, officials said Thursday. 

The bomber attacked the procession around midnight Wednesday in the city of Rawalpindi, said Deeba Shahnaz, a state rescue official.

At least 62 people were wounded by the blast, including six police officers. Eight of the dead and wounded were children, Shahnaz said.

Slideshow: Pakistan: A nation in turmoil

Muhammed Muheisen / AP

Images of daily life, political pursuits, religious rites and deadly violence.

Launch slideshow

Police tried to stop and search the bomber as he attempted to join the procession, but he ran past them and detonated his explosives, senior police official Haseeb Shah said. The attacker was also carrying grenades, some of which exploded, Shah said.

Malala's wounded friends back in Pakistan school

"I think the explosives combined with grenades caused the big loss," said Shah.

Local TV footage showed the scene of the bombing littered with body parts and smeared with blood. Shiites beat their heads and chests in anguish.

"It was like the world was ending," said one of the victims, Nasir Shah, describing the blast. He was being treated at a local hospital for wounds to his hands and legs.

Earlier Wednesday, the Taliban set off two bombs within minutes outside a Shiite mosque in the southern city of Karachi, killing one person and wounding 15 others, senior police official Javed Odho said.

Pakistani Taliban spokesman Ahsanullah Ahsan claimed responsibility for the attacks in Rawalpindi and Karachi.

"We have a war of belief with Shiites," Ahsan told The Associated Press by telephone from an undisclosed location. "They are blasphemers. We will continue attacking them."

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Updated at 8:11 a.m. ET: A suicide car bomber struck early Monday at the gates of Jalalabad airport in eastern Afghanistan, killing nine people in a large blast, officials said.

Among the dead were six civilians, two airport guards and one soldier, Mohammad said. Another six people were wounded, he said.

An AP photographer saw at least four destroyed cars at the gates of the airport.

The Afghan Taliban claimed responsibility for the suicide attack, that they also say killed a number of U.S. soldiers and members of the Afghan interior ministry, a spokesman told NBC News.

"Our suicide bomber carried out suicide attack at a time when the U.S. troops opened the main entrance for change of the night time shift at the airport. Besides American soldiers, a number of Afghanistan interior ministry personnel working (with) the U.S. troops were also killed in the attack," the Taliban spokesman Zabihullah Mujahid told NBC News.

He said it was revenge of the desecration of holy Quran allegedly by U.S. forces at the Bagram airbase.

But NATO forces spokesman Capt. Justin Brockhoff said that no international forces were killed in the early morning attack and that the installation was not breached by the blast.

Escalating violence
The blast comes a day after demonstrators hurled grenades at a U.S. base in northern Afghanistan, and a gun battle left two Afghans dead and seven NATO troops injured Sunday in the escalating crisis over the burning of Muslim holy books at an American airfield.

More than 30 people have been killed, including four U.S. troops, in six days of unrest. Still, the top U.S. diplomat in Afghanistan said the violence would not change Washington's course.

"Tensions are running very high here, and I think we need to let things calm down, return to a more normal atmosphere, and then get on with business," Ambassador Ryan Crocker told CNN's "State of the Union."

"This is not the time to decide that we're done here," he said. "We have got to redouble our efforts. We've got to create a situation in which al-Qaida is not coming back."

Story: Eight US soldiers wounded in Afghan NATO base attack

The attack on the base came a day after two U.S. military advisers — a lieutenant colonel and a major — were found dead after being shot in the head in their office at the Interior Ministry in the heart of the capital. The building is one of the city's most heavily guarded buildings, and the slayings raised doubts about safety as coalition troops continue their withdrawal.

The incident prompted NATO, Britain and France to recall hundreds of international advisers from all Afghan ministries in the capital. The advisers are key to helping improve governance and preparing the country's security forces to take on more responsibility.

A manhunt was under way for the main suspect in the shooting — an Afghan man who worked as a driver for an office on the same floor as the advisers who were killed, Interior Ministry spokesman Sediq Sediqi said. He did not provide further details about the suspect or his possible motive.

Story: Afghan officer sought in connection with US slayings

The Taliban claimed that the shooter was one of their sympathizers and that an accomplice had helped him get into the compound to kill the Americans in retaliation for the Quran burnings.

Afghanistan's defense and interior ministers were to visit Washington this week, but they called off the trip to consult with other Afghan officials and religious leaders on how to stop the violence, Pentagon press secretary George Little said. The Afghan officials had planned to meet with Defense Secretary Leon Panetta and Joint Chiefs Chairman Gen. Martin Dempsey.

The protesters in Kunduz province in the north threw hand grenades to express their anger at the way some Qurans and other Islamic texts were disposed of in a burn pit last week at Bagram Air Field, north of Kabul.

The Associated Press contributed to this report.

Slideshow: Protests erupt over Quran burning

Parwiz / Reuters

Angry afghans attacked U.S. bases after reports of Quran desecration.

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Rachman / EPA

Umar Patek, center, waves as he leaves court in Jakarta, Indonesia, on Monday.

JAKARTA, Indonesia - A militant suspected of building the bombs used in the 2002 Bali attack went on trial Monday on terrorism charges, a year after he was captured in the same Pakistani town where Osama bin Laden was hiding.

Umar Patek is the top remaining suspect in the Bali nightclub bombings, which killed 202 people about a year after the Sept. 11 attacks and brought international attention to an al-Qaida-linked group intent on creating a pan-Islamic state throughout Southeast Asia.

Three masterminds in the attack already have been tried and executed, and authorities have made big strides in dismantling their regional terror group, Jemaah Islamiyah.

But Patek, nicknamed "Demolition Man" by Indonesian investigators, escaped the country after the attack and went on a nine-year flight from justice that took him to the Philippines and Pakistan, allegedly in pursuit of more terror opportunities.

$1 million bounty
Patek was captured in January 2011 in Abbottabad, where U.S. Navy Seals would kill Osama bin Laden just a few months later. Patek was then one of Asia's most wanted terror suspects, with a $1 million bounty on his head.

The trial could shed light on what Patek was doing in Abbottabad.

Indonesia's Defense Minister Purnomo Yusgiantoro has said he was believed to be trying to meet with bin Laden, but Patek has denied that, saying he was on way to seek shelter in Afghanistan. U.S. and Pakistan investigators have suggested Patek's stay in Abottabad was pure coincidence.

Patek, who also is accused in a string of Christmas Eve bombings at churches in 2000 that claimed 19 lives, was tightly guarded as he entered the West Jakarta District Court on Monday.

He smiled to reporters and photographers but did not respond to questions shouted by journalists. Wearing a white robe and a white skullcap, Patek, 45, sat quietly as the indictment was read out by state prosecutors, led by Bambang Suharijadi.

"His involvement in the Bali bombing as well as the church attacks were not as big as is being described," Patek's chief lawyer Ashluddin Hatjani told reporters afterward. "We will challenge that in a defense plea next week."

Patek, whose real name is Hisyam Bin Alizein and who has several aliases, could face death by firing squad if convicted of the various charges against him. The indictment includes charges of premeditated murder, hiding information about terrorism, illegal possession of explosives and conspiracy to commit terrorism.

Filing cabinets
After the charges were read, presiding judge Lexsy Mamoto adjourned the trial until next Monday. Patek then shook hands will all of the prosecutors except Rini Hartati, the only woman member of the team. Hartati held out her hand but Patek rejected it by putting his right hand on his chest.

In a re-enactment organized by police in Bali while he was in custody there, Patek showed how he and other conspirators stashed a 1,540-pound bomb in four filing cabinets, loaded it in a Mitsubishi L300 van along with a TNT vest bomb.

The van was detonated outside two nightclubs on Bali's famous Kuta beach.

Patek left Bali a few days before the Oct. 12 attacks were carried out, while Imam Samudra and two other masterminds of the Bali attacks — brothers Amrozi Nurhasyim and Ali Ghufron — were caught, tried and executed.

Patek later told interrogators that he and other militants involved in the Bali bombing met a week after the attack to celebrate and assess how they could have done it better.

"The meeting was led by Muklas to evaluate the shortcomings of the execution of the suicide bombings," he was quoted as saying in an interrogation report obtained by The Associated Press. "The meeting was also to thank God and eat together for the success of the bombings that we had carried out in Bali."

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Updated at 9:30 a.m. ET

DAMASCUS - A bomb that ripped through a police bus in Syria's capital killed 26 and wounded 63, the country's interior minister said, vowing an "iron fist" response to the carnage.

Interior Minister Ibrahim al-Shaar, quoted by state television, said 26 people had been killed in the blast in the Maidan district of Damascus, including 15 who could not be identified because their bodies had been shredded in the blast.

"We will strike back with an iron fist at anyone tempted to tamper with the security of the country or its citizens," he said.

Updated at 6:59 a.m. ET

DAMASCUS -- An explosion ripped through a police bus in the center of Syria's capital Friday, killing at least 10 people in an attack authorities blamed on a suicide bomber, a Syrian official and state-run TV said.

However, Reuters reported that local news station Addounia put the death toll at 25. Addounia said 46 others were wounded. 

Although the nearly 10-month-old uprising in Syria has convulsed many parts of the country, Damascus has been relatively quiet under the tight control of ruthless security agencies loyal to President Bashar Assad.

The government has long contended that the turmoil in Syria this year is not an uprising but the work of terrorists and foreign-backed armed gangs.

• Report: Syria troops fire on Arab League monitors

The opposition has questioned those allegations. It has hinted that the regime itself could have been behind a Dec. 23 bombing targeting the country's intelligence agencies. At least 44 people were killed and 166 others were injured in that attack.

Published at 5:47 a.m. ET: A suicide bomber killed and wounded dozens of people in central Damascus, Syrian state TV said Friday.

Footage broadcast by Syria Television showed the shattered windows of what appeared to be a police bus.

State TV said the explosion went off at an intersection in the neighborhood of Midan, while scores of people were in the area. It said most of the casualties were civilians.

Syria has banned most foreign journalists from the country and prevented independent reporting.

The explosion comes two weeks after two blasts in Damascus targeting security buildings killed 44 people.

A Syrian official, speaking on condition of anonymity because he was not allowed to talk publicly to the media, said the target of the attack appeared to be a bus carrying police officer.

"This is a criminal terrorist act," a man shouted in footage aired on Syria TV.

For months, President Bashar Assad has used tanks and troops to try to crush street protests inspired by other Arab uprisings.

According to the U.N., more than 5,000 people have been killed during the uprising against the Assad regime.

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The Associated Press and Reuters contributed to this report.