Police officer Ishrat Yar says the attack near the main northwest city of Peshawar started late on Sunday night and triggered a gunbattle that lasted for several hours. The militants were armed with heavy machine guns, rocket-propelled grenades, hand grenades and assault rifles.
Mr Yar also says 12 policemen were wounded in the attack in the small town of Matni, some 20 kilometers (12 miles) south of Peshawar.
One of the beheaded policemen was a senior official who commanded several police stations in the area.
Yar says the militants burned the police station and four police vehicles before they escaped.
Edited By Cen Fox Post Team
