Three bombs exploded during a Shia Muslim religious procession in the eastern Pakistani city of Lahore, killing 25 people and wounding about 150 others, officials say.
The explosions appeared to be the latest in a string of attacks by Sunni extremists against the minority Shias they consider infidels.
Allied with al-Qaeda and the Taliban, the bombers are also seeking to destabilize Pakistan's US-backed government.
The blasts were the first major attacks since Pakistan was hit by devastating floods more than a month ago.Lahore, the country's political capital and home to much of its military elite, has been regularly targeted by militants over the past two years.
The bombs exploded at three separate sites as 35,000 Shias marched through the streets of Lahore in their traditional mourning procession for the caliph Ali, one of Shia Islam's most respected holy men.
Prime Minister Yousuf Raza Gilani condemned the blasts in a statement and said the attackers would not escape justice.
