QUETTA, Pakistan - Powerful aftershocks rocked the border between Iran and Pakistan Wednesday, a day after a major earthquake tore through the region, collapsing buildings and killing at least 39 people and injuring more than 170.

The Pakistani town of Mashkel was “totally destroyed,” according to a local journalist at the scene. Reporter Farooq Kabdani said almost all of the town's mud houses and shops had collapsed. He suggested the death toll could climb as about 25 people remained missing.

Tuesday’s major quake, rated at magnitude 7.8 by the U.S. Geological Survey and 7.5 by the European-Mediterranean Seismological Agency, was centered about 50 miles east of the city of Khash, Iran, but shook tall buildings as far away as New Delhi, nearly 1,500 miles away.

Fifteen seriously injured victims have evacuated to the Central Military hospital Quetta by the Pakistan Army.The victims range in age from 3 to 50 years old.

It was described by Iranian media as the worst in 50 years, but the majority of confirmed casualties appeared to be on the Pakistan side of the border.

Officials in Mashkel District in Pakistan's Balochistan province said 38 people were killed there, while 170 were injured, including 30 in critical condition.

Banaras Khan / AFP - Getty Images

Earthquake survivors stand on the rubble of their collapsed mud houses in the Mashkel area of southwest Pakistan, Wednesday.

Iran’s state-run Press TV reported one confirmed Iranian death, noting that initial reports had suggested a much higher death toll. A hospital in the Iranian city of Saravan, which is close to the epicenter, reported 10 fatalities on Tuesday. 

Washuk Khan Mohammad, the local deputy commissioner, said the Mashkel area was hit by two more aftershocks on Wednesday, which he said measured 6.5 and 4.4 on the richter scale, causing more damage.

Conditions in Mashkel, which lies south-west of Quetta, were described as “miserable” by Kabdani. The area is “totally destroyed,” he added.

While the earthquake's epicenter was in a thinly populated area, the USGS estimated that about 400,000 people live in areas where the shaking was very strong to severe; 1.7 million live in areas where it was considered strong; and another 2.6 million are in territories where it was classified as moderate.

The State Department expressed its condolences for the lives lost in the earthquake.

"The United States sends our deepest condolences for those lost in the earthquake in southeastern Iran and western Pakistan today," a statement released Tuesday read. "Our thoughts are with the families of those who were killed, those who were injured, and with those communities that have suffered damage to homes and property. We stand ready to offer assistance in this difficult time."

The Tehran Geophysics Center said the quake lasted 40 seconds and described it as the country's strongest in more than 50 years.

An April 9 earthquake near the country's only nuclear power plant killed 37 people and injured at least 850 more, leaving entire villages devastated.

Despite the scare caused by that quake, Iran pledged that it would continue to build more reactors in the heavily seismic region, which is hundreds of miles from the site of the latest temblor, on the other side of the country's south.

Iran has a history of devastating earthquakes. A magnitude-6.6 quake in 2003 killed an estimated 31,000 people, and a 7.5 in 1990 killed as many as 50,000, according to the USGS.

NBC News' Ali Arouzi contributed to this report.

Related:

What caused latest deadly earthquake in Iran?

This story was originally published on Wed Apr 17, 2013 5:50 AM EDT

Arshad Butt / AP

Pakistani relatives of Saturday's bombing victims mourn next to the bodies in a mosque in Quetta, Pakistan, Feb. 17. Angry residents demanded government protection from an onslaught of attacks against Shiite Muslims a day after scores of people were killed in a massive bombing that a local official said was a sign that security agencies were too scared to do their jobs.

Dozens of people including schoolchildren 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.

-- By Gul Yousufzai, Reuters

Read the full story.

Naseer Ahmed / Reuters

A man prepares graves for the burial of victims.

Naseer Ahmed / Reuters

A girl cries during the funeral for victims of Saturday's bomb attack.

Musa Farman / EPA

A Pakistani paramilitary soldier inspects the belongings of a boy at the scene.

Yslb Pak / Zuma Press

Fire rages from destroyed buildings Feb. 16 at the site of the attack.

Naseer Ahmed / Reuters

Smoke rises in a Shiite Muslim area after the attack Feb. 16.

Naseer Ahmed / Reuters

A paramilitary soldier reacts as he asks civilian to leave the scene of a bomb explosion in Quetta on Thursday.

Updated 7 p.m. ET: The death toll from twin bombings on a billiards hall Thursday in southwest Pakistan rose to 81, with at least 120 more injured, according to a senior police official.

Police officer Hamid Shakeel said the bombs went off about 10 minutes apart, The Associated Press reported, with the second blast causing the building to collapse. Several nearby shops, homes and offices were also damaged.

Lashkar e Jhangvi, a Sunni Muslim militant organization aligned with al-Qaida, took responsibility for the attack. 

Many of the dead and wounded were Shiite Muslims, officials said; police officers, journalists and rescue workers who responded to the initial explosion were also among the dead, the AP reported.

The Associated Press interviewed Ghulam Abbas, a Shiite who lives some 150 yards from the pool hall. He said he was at home with his family during the first blast, and was thinking about going to the scene when the second bomb went off.

"The second blast was a deafening one, and I fell down," he told the AP. "I could hear cries and minutes later I saw ambulances taking the injured to the hospital."

The pool hall assault in Quetta, the capital of Baluchistan province, was the third terrorist attack of the day in Pakistan.

Earlier, a bomb targeting paramilitary soldiers in a commercial area in Quetta killed 12 people and wounded more than 40 others, Shakeel said, the AP reported.

Elsewhere in Pakistan, a bomb in a crowded Sunni mosque in the northwest city of Mingora killed 22 people and wounded more than 70, said senior police officer Akhtar Hayyat, the AP reported. 

It was one of the country's deadliest days in recent years.

The Pakistani government's failure to crack down on the killings of the country's Shiite were criticized by Human Rights Watch, which said more than 400 Shiites were killed in targeted attacks in Pakistan in 2012.

"2012 was the bloodiest year for Pakistan's Shia community in living memory and if this latest attack is any indication, 2013 has started on an even more dismal note," Ali Dayan Hasan, Pakistan director at Human Rights Watch, told the AP. 

"As Shia community members continue to be slaughtered in cold blood, the callousness and indifference of authorities offers a damning indictment of the state, its military and security agencies," Hasan said. "Pakistan's tolerance for religious extremists is not just destroying lives and alienating entire communities, it is destroying Pakistani society across the board."