A car bomb killed at least 20 people and wounded scores in the northwestern Pakistani city of Peshawar today, officials said.
The blast occurred near an assembly hall of minority Shia Muslims in a crowded part of the city. One building collapsed in flames and several others were badly damaged and on fire.
"It shook the entire area like an earthquake," said resident Rahim Gul as he tried to remove rubble with his bare hands.
"It was a huge and terrible explosion. As we reached here it was all burning. There was rubble all around." Khizar Hayat, the chief doctor at the city's main government hospital, said at least 20 people had been killed and 50 wounded, 20 of them seriously.
He appealed to townspeople to donate blood for the wounded.
The blast was caused by an explosives-laden car parked near the assembly hall. Police said it was not clear whether the explosives were detonated by a suicide bomber or by remote control.
The blast knocked out power supplies in the street, and rescue workers were hampered by a throng of angry and wailing people.
North West Frontier Province police chief Malik Naveed Khan said the bomb contained 20-25 kilogram of explosives.
Sunni Muslim militant groups have launched several gun and bomb attacks on minority Shias in the northwest in recent weeks in worsening sectarian violence.
Earier today a suicide car bomb killed at least six people in an attack apparently aimed at Shias in the Orakzai ethnic Pashtun tribal region, also in northwest Pakistan.
The bomber drove towards the scene of a tribal council meeting, or jirga, called by Shia Muslims to settle a dispute with majority Sunni Muslims.
"The bomber tried to drive into a market in a Shi'ite neighbourhood where the meeting was taking place but blew up his car when police tried to stop him at a checkpoint," said an intelligence agency official who declined to be identified.
A government official said seven people had been killed in the attack in Kalaya, the main town in Orakzai, while resident Mohammad Hanif said he had seen six bodies at the scene.
"Some of them were policemen," Mr Hanif said by telephone.
Thousands of people have been killed in tit-for-tat sectarian violence going back to the 1980s.
The majority of Pakistan's Muslims are Sunni but around 15 per cent of the nation of 170 million people are Shia.
Sectarian violence has flared in northwest Pakistan over the past year, mostly in the Kurram region on the Afghan border.
Security analysts say al-Qaeda and Taliban militants, who are Sunnis and are bitterly opposed to Shias, have stirred up sectarian strife as they expand their influence through the northwest.