A bomb blast targeted a police vehicle in Bajaur on Monday, killing at least six police officials and injuring 28.

The death toll rose to six after policeman Imran passed away in a Peshawar hospital, according to police.

Rescue 1122 sources said that the blast happened in Bajaur’s tehsil Mamund. The officials were travelling for duty with polio vaccination teams.

The bodies of those killed in the attack as well as those who were injured have been shifted to hospitals. At least two of those injured in the attack are in critical condition.

The new year’s first polio vaccination campaign is set to begin in Khyber Pakhtunkhwa on Monday. The campaign will target 7.4 million children throughout the province.

The campaign will be carried out over seven days in Peshawar and Khyber, and for five days in other districts. Lakki Marwat and Waziristan will also be covered in the campaign.

A total of 31,505 polio workers will be on duty to administer the vaccine and over 50,000 security officials have been appointed to assist them.