Police official Arif Khan says Sunday's attack took place in Kohat district, some 90 kilometers (56 miles) south of Peshawar in Khyber Pakhtunkhwa province. He says police launched a hunt for the attackers, who fled.
Khan says the police were returning to their station following a patrol when they were attacked. The area police chief, his second-in-command and two constables were killed, AP reported.
No group has claimed responsibility for the attack. However, Jamaat-ul-Ahrar, a breakaway faction of the Pakistani Taliban, has claimed responsibility for previous similar attacks in the province, which borders Afghanistan.