PESHAWAR — Gunmen riding on a motorcycle shot and killed a police officer protecting polio workers during a UN-backed vaccination campaign in northwestern Pakistan on Tuesday, the police said. The attack took place as dozens of polio workers — including several women — were going door-to-door to vaccinate children in Gullu Dheri village of Swabi district in Khyber Pakhtunkhwa province, said senior police officer Izhar Shah. None of the polio workers the police officer was protecting were hurt in the attack, he said. “The polio workers were terrified and immediately went back to their homes after the attack,” Shah told The Associated Press. “The anti-polio drive in that village has been suspended.” Elsewhere in the northwest, a man wounded a polio worker, Mohammed Mumtaz, with an axe. Mumtaz was marking houses in Machi village to indicate where vaccines had been administered, he said. The attacker became irate after his door was marked and swung the axe at Mumtaz, injuring him on his left arm. The attacks occurred on the second day of a three-day campaign against polio that was launched by the provincial government. No one claimed responsibility for the shooting in Gullu Dheri, but suspicion fell on militants. Some militants 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. — AP