At least 31 people were killed and over 100 others injured in a twin suicide attack inside a police residential compound in Pakistan's northwestern Khyber Pakhtunkhwa Province on Friday, officials said.

The incident happened in Kohat district, where one of the bombers rammed an explosive-laden vehicle into a mosque adjacent to the compound's gate before detonating it, Inspector General of Police of the province Zulfiqar Hameed told the media.

Another bomber blew himself up near a building that houses offices of the special branch of police, he added.