A suicide bomber struck a mosque in north-west Pakistan during prayers today, causing the roof to collapse and killing at least 50 people.
The explosion occurred in Darra Adam Khel, an area near Pakistan's tribal regions where Taliban-led militants have been active.
Hundreds of worshippers had gathered at the Sunni mosque for the most popular prayer session of the week.
The mosque's roof caved in, trapping people in debris. At least 80 people were injured.
People in private vehicles rushed the wounded to hospitals in Peshawar, the main city in the north-west, TV footage showed.
"The blast tossed me up. I fell down," said Mohammad Usman, 32, a schoolteacher with wounds on his head and arms as he lay on a hospital bed in Peshawar. "Later, it was just like a graveyard."
Haji Razaq Khan, a member of Pakistan's Senate from Darra Adam Khel, said a tribal elder who had been encouraging people to stand against the Taliban had a guest room next to the mosque and may have been the target. It was not immediately clear whether that elder, Malik Wali Khan, was among the victims.
Islamist militants have frequently targeted tribal leaders who have taken stands against them.
Provincial information minister Mian Iftikhar Hussain called the militants "beasts" who were lashing out at Pakistan's crackdown against them.
"This is part of international terrorism. America, Pakistan and Afghanistan are the main players who need to work closely and more aggressively to root out this menace," said Hussain, whose only son was killed by militants earlier this year.
Today's blast was the latest in a series of attacks at mosques and Sufi shrines in Pakistan, and underscored the relentless security challenge to a nation where Islamist militants have thrived despite US-supported army offensives against them.