A bomb blast inside a Shi'ite mosque during evening prayers killed at least 14 people on Monday in the southern city of Karachi, where a senior cleric from Pakistan's majority Sunni sect was shot dead a day earlier.
Doctors said they had counted 14 dead and hospitals had admitted more than 55 wounded, while wailing men and women searched in the darkness for relatives lost in the wreckage under the cracked dome of the city center mosque.
An angry crowd outside the mosque set fire to nearby vehicles and prevented police from approaching the scene, letting through only ambulances.
Karachi had feared fresh inter-Muslim sectarian violence after the killing on Sunday of Mufti Nizamuddin Shamzai, a radical Sunni preacher, and thousands of police were on duty at the city's mosques in anticipation of a backlash.
The government's chief spokesman told Geo Television President Pervez Musharraf planned to take tough measures to restore order in the city.
``I will take serious action, this is the second incident within 24 hours, following Mufti Shamzai's killing,'' Information Minister Sheikh Rashid Ahmed quoted Musharraf as saying.
The Ali Raza Imam Bargah mosque, the target of the bomb, was less than a mile away from where Shamzai, a pro-Taliban cleric who called for ``jihad,'' or holy struggle, against the United States, was killed.
One worshipper, a man called Saddiqan, said he was on his way into the mosque when the explosion knocked him off his feet.
``I saw two dead bodies without limbs lying on the ground,'' he said.
Anger among the several hundred people gathered outside the bombed mosque spilled over and a mob set fire to a nearby petrol pump, a police van and a private car.
``I can hear gun shots and the angry crowd is torching cars and tires, while a gas station has already been burned,'' a Reuters correspondent at the scene said.
Police were unable to get near the mosque because the crowd was letting in only ambulances.
A suicide bomber killed 24 people and wounded 125 in an attack on another Shi'ite mosque in Karachi on May 7.