The blasted remains of a Pakistani police patrol vehicle.
Eleven officers died when a suicide bomber rammed a car packed with explosives into their pickup truck.
The attack happened in the Khyber tribal region, on the road leading through the Khyber Pass to the Afghan border.
Seven passersby and a soldier also perished in the blast, which injured many.
The attack came as rumors about the death of the Pakistan Taliban leader intensified.
Pakistan says it has credible information suggesting that Hakimullah Mehsud has died after being wounded last month in a U.S. drone attack.
The Taliban has denied the claim.
But speculation on his fate has mounted after another Taliban official, requesting anonymity, told journalists the leader had died of wounds while being taken to Karachi.
Mehsud's predecessor was also killed in a drone strike in August.
The Pakistani Taliban have lost much ground in military offensives over the past year, but the Khyber attack is a powerful reminder of the militant threat facing Pakistan.