Islamabad  - At least seven people, including five policemen, were killed and more than two dozen injured Sunday when a bomb blast targeted a police vehicle in north-west Pakistan, a security official said.

The explosion in Dera Ismail Khan district of Pakistan's North- Western Frontier Province destroyed the vehicle.

"There was, first, a low-intensity blast, perhaps carried out with a hand-grenade, that injured three people outside a restaurant," a security official said on condition of anonymity.

"When several policemen reached the site in a van to investigate the incident, there was second explosion of high intensity. Five policemen inside the van were killed and three more injured, while two civilians dinning inside the restaurant were killed and more than 25 were injured."

It was not immediately clear whether the second blast was a suicide attack or a roadside bombing. (dpa)