Residents of Karachi gathered after a bomb exploded on Sunday.
ISLAMABAD, Pakistan — Two powerful explosions ripped through a predominately Shiite neighborhood in Karachi on Sunday evening, in a bomb attack that killed at least 37 people and wounding at least 90, police and rescue officials said.
There was no immediate claim of responsibility, but the attack fit the pattern of a brutal militant campaign of violence against Pakistan’s Shiite minority over the past year that is widening the country’s sectarian divisions.
The blasts occurred in Abbas Town, a large Shiite district of Karachi, badly damaging two apartment blocks. Several apartments caught fire as gas lines ruptured from the force of the bombs.
Rescue workers rushed the dead and wounded to local hospitals. With dozens more people trapped under the wreckage, the death toll was expected to rise.
Police officials said the first blast, which was heard miles away, appeared to have been set off by a car bomb. The nature of second blast remained unclear; some police officials speculated that it may have been caused by a gas cylinder.
Fayaz Leghari, the provincial police chief, told local news media that the city police force had been on alert in anticipation of such an attack given the Sunni militant campaign against Shiites. The most notorious group, Lashkar-e-Jhangvi, claimed responsibility for two blasts in the western city of Quetta that killed almost 200 people, mostly from the Hazara Shiite minority. But there have been signs that such Sunni extremist groups are also bent on stepping up their bloody campaign in Karachi, Pakistan’s largest and most volatile city.
Mr. Leghari said the Karachi police had apprehended two explosives-laden vehicles in recent weeks but denied suggestions there had been specific intelligence that forewarned Sunday’s blast. Last month, Interior Minister Rehman Malik warned of possible attacks in Karachi and Quetta.
President Asif Ali Zardari and Prime Minister Raja Pervez Ashraf, who was visiting Karachi at the time of the blasts, condemned the attack. Mr. Ashraf said those targeting innocent civilians were “serving the interests of anti-state and antisocial elements,” according to state-run news agency, Associated Press of Pakistan.
Residents of Abbas complained to reporters that, two hours after the blast, a single government official had yet to reach the neighborhood.
Local television news networks reported that a large contingent of city police had been busy in protocol and security duties at the engagement ceremony of Sharmila Faruqui, a provincial minister, and Hasham Riaz Sheikh, an aide to President Zardari.
Declan Walsh contributed reporting.