A suicide bomber killed at least 25 people in a mosque packed with worshippers and wounded more than 50 when he blew himself up during Friday prayers in the eastern Pakistani town of Sialkot, police said.
More than 1,000 people from Pakistan's Shi'ite Muslim minority were crowded into the Zainabya mosque when the blast ripped through the building, police said.
"It was a suicide attack," Nisar Ahmed Saroya, district police officer for Sialkot, told Reuters. "It was a massive explosion which was heard several miles around.
"The floor of the mosque is strewn with blood and human flesh," Saroya said, adding the death toll had risen to 25. A toll given by ambulance workers was slightly higher.
Police in the town, 170 km (100 miles) southeast of the capital Islamabad, put the number of wounded at more than 50.
The explosion blew a crater more than 75 cm (2 feet) deep and 90 cm (3 feet) wide, said police.
A second bomb weighing around 5 kg (11 lb) was found in a briefcase at the scene and defused by a bomb disposal squad.
"There were two bombs and one did not explode," Amjad Karim Butt, a senior police official, told Reuters.
Police sources said eight suspects had been rounded up. Army and police cordoned off the mosque in a busy neighborhood.
Information Minister Sheikh Rashid Ahmed told Reuters the attack might be retaliation for the killing last Sunday of the most wanted Pakistani militant, Amjad Hussain Farooqi.
Seen as the main link between Osama bin Laden's al Qaeda and local militant groups, Farooqi was a key suspect in two assassination attempts on President Pervez Musharraf last December.
"It could be a possible reaction to that killing," said the minister. "It is an act of terrorism aimed at destabilizing the country."
ANGRY RAMPAGE
Several hundred angry Shi'ites rampaged through Sialkot after the explosion. The mob set fire to a petrol station and two police vehicles and hurled stones at buildings in the neighborhood, police said.
Allama Saeed Hasan Sherazi, a Shi'ite cleric who arrived at the mosque, described blood and flesh on the ceiling and walls.
"I saw bodies and injured on the floor," he said. "People were shouting and screaming... enemies of Islam and Pakistan are responsible for this."
No group immediately claimed responsibility for the attack. Sunni Muslim extremists were blamed for a series of attacks on Shi'ite mosques in the southern port city of Karachi earlier this year.
Shi'ite Muslims account for 20 percent of Pakistan's 150 million people, and Sunni Muslims almost all the rest.
Some Sunni groups have forged closer links with the al Qaeda network amid anger over Musharraf's support for the U.S.-led war on terror since the Sept. 11, 2001 attacks.
Karachi was put on alert against a possible terrorist attack this week after the shooting of Farooqi, a known leader of Lashkar-e-Jhangvi, a splinter faction of another outlawed radical Sunni group, Sipah-e-Sahaba Pakistan.
Both groups consider Shi'ite Muslims to be heretics and Lashkar-e-Jhangvi is blamed by police for many of the killings of Shi'ites in recent years.
Farooqi was also wanted in connection with the kidnapping and murder of U.S. journalist Daniel Pearl in 2002.
The Information Minister said the attack could be a message of defiance to Musharraf after a trip to the West during which he agreed with Indian Prime Minister Manmohan Singh to seek peace between the two countries.
During the trip Musharraf expressed his support for the war on terror, although he called on Washington to change its policy toward Israel and said the plight of the Palestinians was a root cause of Muslim anger against the United States.
"President Pervez Musharraf has just returned from a successful visit to the United States and Europe and this explosion was meant to undermine this trip," the minister said.