A suicide bomber struck a police vehicle at a city in the restive northwest Pakistan on Tuesday, killing at least five persons, including a child, and injuring 15 others.

Deputy Inspector General of Police Iftikhar Khan said the bomber, who was on foot, targeted the vehicle near the main police station of Bannu in Khyber-Pakhtunkhwa province.

Other officials said a police constable, a child and three civilians were among those killed. Four persons were killed instantly while a man succumbed to his injuries in hospital.

The 15 injured people were taken to a nearby hospital, where an emergency was declared.