Islamabad, May 25 : Three policemen were injured in Pakistan's Khyber Pakhtunkhwa province on Thursday when unidentified gunmen opened fire at a polio immunisation team. The cops were deployed for the security of polio workers during a door-to-door campaign to administer vaccinate children when they were attacked, the Khyber police said in a statement. The polio team was safe and the immunisation drive has been temporarily suspended in the area. The injured policemen were shifted to a nearby hospital, whereas a search operation has been kicked off in the area to arrest the fleeing militants. No group has claimed responsibility for the attack yet. A five-day anti-polio drive in 12 districts of the province kicked off on Monday, with an aim to vaccinate over 3.5 million children under five years of age. According to a recent report from the World Health Organization, all the new polio cases reported in Pakistan since January 2021 are from seven polio-endemic districts in the southern part of Khyber Pakhtunkhwa province. Pakistan is one of the two remaining countries in the world where polio is still categorised as an endemic viral infection,the other one being Afghanistan. In 2021, there was one documented case in the country and 84 in 2020. In 2019, there were a record 147 cases. Last year, there was 20 cases. /IANS