A powerful explosion struck a mosque near police offices during Friday prayers in Kohat district, in Pakistan's northwestern Khyber Pakhtunkhwa province, killing and wounding worshippers, according to police and rescue officials.

The mosque is located near the old Police Lines in Kohat, about 60 kilometres southwest of the provincial capital Peshawar. According to preliminary information, an attacker rammed an explosives-laden vehicle into the mosque premises, after which an exchange of fire with armed militants took place. A police chief said the vehicle hit the gate and then exploded, and that firing also occurred.

Accounts of the death toll differed. A senior rescue official said at least seven people were killed and more than 30 wounded, most of them worshippers. The police chief said at least 16 people were killed, including five police personnel and 11 civilians. The district health officer in Kohat said 21 people were killed, including 16 police personnel and five civilians, and 78 others were injured.

Casualties were taken to a nearby hospital, where authorities declared an emergency to handle the influx of patients. Police said the explosion was powerful enough to badly damage nearby shops and homes. Footage posted on social media showed the mosque's roof had collapsed, and rescuers and residents were seen pulling injured people from the rubble and carrying them to ambulances.

A little-known militant group, Ittehad-ul-Mujahideen Pakistan, claimed responsibility, according to police. No further details on the claim were immediately available in the accounts.

The mosque sits near a building housing police offices, and the reported victims included both police personnel and civilians. The blast occurred in a province bordering Afghanistan.