A remote-controlled improvised explosive device was used to target the vehicle in Dawezai area of Mohmand tribal agency, officials said.
Two security personnel were killed and nine others injured in the attack, they said.
Three members of a "peace committee" or anti-Taliban militia were among the injured, the officials said.
The vehicle was destroyed in the blast.
The injured were taken to a hospital in Ghalanai, the main town of the region.