The police convoy was attacked at Mattani area late last night. Six policemen were killed instantly while one more died in hospital today, officials said.
Kohat district police chief Dilawar Bangash was among the injured. Bangash was driving from Peshawar to Kohat when his convoy was ambushed on the Indus Highway. The militants fired several rockets at the convoy and destroyed one vehicle.
An injured driver drove Bangash to Kohat and both of them were admitted to a military hospital, officials said.
No group claimed responsibility for the attack though such incidents are usually blamed on the banned Tehrik-e-Taliban Pakistan.