At least four policemen were killed and six others injured on Thursday when unidentified gunmen set off a bomb and then opened fire at their vehicle deployed for election security in Pakistan's restive Khyber-Pakhtunkhwa province, bordering Afghanistan.

According to police, the vehicle was stationed in the jurisdiction of Kalachi police station in Dera Ismail Khan. The policemen were deployed for the security of Graha Aslam polling station, the Express Tribune newspaper reported.

The attack happened a day after at least 30 people were killed in twin terror attacks in the restive Balochistan province.

Indiscriminate shooting was reported in the area after the bomb attack, the paper said.

The bodies of the victims of the attack and the injured were shifted to the hospital.

Security forces have cordoned off the area and started a search operation.

No group or individual claimed responsibility for the attack but the area is a former stronghold of the banned Tehreek-e-Taliban Pakistan. The group carried out multiple attacks targeting security forces in recent years.

Except for the headline, this story has not been edited by The Telegraph Online staff and has been published from a syndicated feed.