Islamabad, Dec 19 (IANS): Two policemen were killed when gunmen lodged an attack on a polio vaccination team in Pakistan's Khyber Pakhtunkhwa province, it was reported on Thursday.

The policemen were part of a nationwide drive launched this week to inoculate tens of millions of children in Pakistan - one of only two countries where the crippling disease remains endemic, reports The Express Tribune.

"The incident took place on Wednesday in Maidan area. The policemen were on their way to a basic health unit when they were targeted," a police official said.

"No officials from the polio vaccination team were hurt as they were at a distance. However, the suspects managed to escape from the scene."

There was no immediate claim of responsibility for the Wednesday's killings.

The attack comes during a devastating year in Pakistan's long fight against the disease, with at least 104 cases reported in 2019 so far.

Last year, just 12 cases were reported.

Vaccination campaigns have faced stubborn resistance for years in Pakistan, with many refusing to have their children inoculated because of misinformation and conspiracy theories.

Wednesday marked the third day of the five-day polio campaign.

Around 22,925 teams were constituted to vaccinate 6.75 million children below the age of five. The campaign is focused on reaching and vaccinating every child in order to stop the transmission of the virus as well as its outbreak in the region.