A police constable was killed when unidentified gunmen opened fire at an anti-polio vaccination team in Mardan, officials said on Tuesday.
Police said the attack took place in Ghalla Dera area of Mardan when a team of lady health workers was tending to duty.
The workers remained unhurt and were sent back to their unit, police said, adding that the anti-polio campaign continued in other parts of the province.
The body of the deceased policeman was shifted to the District Headquarters Hospital Mardan.
A similar incident took place in Swabi on January 29 when unidentified gunmen attacked a polio immunisation team in Gullu Dheri area, killing a policeman who was escorting the team.
Authorities had ordered police to provide security to anti-polio teams in the terrorism-hit province after deadly attacks on campaigners across the country.
Pakistan is one of three countries where the crippling disease is endemic.
Suspicion for attacks falls on militants, who oppose the vaccination campaign, accuse health workers of acting as spies for the US and claim the polio vaccine is intended to make Muslim children sterile.
No group has claimed responsibility for the attack so far.
