KARACHI, Pakistan — A car bomb exploded outside a mosque Sunday, killing 37 people and wounding 141 in a Shiite Muslim neighborhood in the southern Pakistan city of Karachi — the third mass casualty attack on the minority sect this year.
No one had taken responsibility for the bombing, but Shiite Muslims have been increasingly targeted by Sunni militant groups in Karachi, Pakistan's economic hub and site of years of political, sectarian and ethnic violence, as well as other parts of the country.
The bomb exploded outside a Shiite mosque as people were leaving evening prayers. Initial reports suggested the bomb was rigged to a motorcycle, but a top police official, Shabbir Sheikh, said an estimated 220 pounds of explosives were planted in a car.
Col. Pervez Ahmad, an official with a Pakistani paramilitary force called the Rangers, said a chemical used in the blast caught fire and spread the destruction beyond the blast site. Several buildings were engulfed in flames.
Men and women wailed and ambulances rushed to the scene where residents tried to find victims buried in rubble. The blast left a crater that was yards wide and more than 4 feet deep.
"I was at home when I heard a huge blast. When I came out, I saw there was dust all around in the streets. Then I saw flames," said Syed Irfat Ali, a resident who described how people were crying and trying to run to safety.
A top government official, Taha Farooqi, said at least 37 people were confirmed dead and 141 more were wounded.
Two attacks against a Shiite community in southwestern city of Quetta killed nearly 200 people this year.
Sunni militants linked to al-Qaida and the Taliban view Shiites, who make up about 20 percent of Pakistan's population of 180 million people, as heretics.