At least 50 people have been killed and up to 100 others injured in a bomb blast at a Sunni mosque in northwest Pakistan during Friday prayers, officials have said.
There are fears the death toll from the explosion could rise further.
"There were more than 100 people inside the mosque. The roof of its main hall collapsed after the blast. Several people are buried under the debris," a local official told the AFP news agency.
"There are blood and body parts everywhere. Elderly people and children are among the dead and wounded. I have not seen such a tragic scene in my whole life,'' Zafar Khan, a villager, was quoted by the AP news agency as saying.
Possible target
The bomb exploded in Darra Adam Khel, an area near Pakistan's tribal regions, where fighter groups have been active.
Kamal Hyder, Al Jazeera's correspondent in the capital, Islamabad, said the area has seen trouble between the Pakistani Taliban and pro-government tribal groups.
He added those wounded in the blast are being taken to the main northwest city Peshawar for treatment.
Haji Razaq Khan, a member of Pakistan's Senate from Darra Adam Khel, was cited by AP as saying 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 clear whether that elder, Malik Wali Khan, was among the victims.
However Khalid Umarzai, a regional administration chief, suggested the attack could have been in retaliation for military operations in the area targeting fighters.
In October, a bomb attack at a Sunni mosque on the outskirts of Peshawar killed three people and wounded 22. It also occurred during Friday prayers.
