PESHAWAR, Pakistan (AP) — Attackers armed with guns and hand grenades ambushed a police van assigned to guard polio workers in northwestern Pakistan, wounding five policemen, authorities said.

Police returned fire after coming under attack near a bridge in Dera Ismail Khan, a district in Khyber Pakhtunkhwa province, according to local police chief Aman Ullah.

The police chief, who was traveling with the convoy to a nearby vaccination site, said between six to eight suspected militants ambushed them, opened fire and threw hand grenades at the police van.

No group claimed responsibility for the attack but Islamic militants often target polio teams and police protecting them, falsely claiming the vaccination campaigns are a Western conspiracy to sterilize children. The latest anti-polio campaign started this week, the first in 2023.

In late November, a Taliban suicide bomber blew himself up near a truck carrying police officers on their way to protect polio workers in the southwestern city of Quetta. A police officer in the truck was killed, as were three members of a family traveling in another car next to the truck.

The Pakistani Taliban claimed the Nov. 30 attack. A month earlier, in October, gunmen riding on a motorcycle shot and killed a police officer assigned to guard a polio vaccination team in southwestern Baluchistan province.

Pakistan, which along with neighboring Afghanistan is the only country where polio remains endemic, regularly launches vaccination campaigns. The latest, five-day campaign started this week in northwestern Pakistan and is the first in 2023.

Since last April, Pakistan has registered 20 new polio cases — all in the northwest, where parents often refuse to inoculate children. The outbreak has been a blow to the government efforts aimed at eradicating the disease.

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