Seven policemen guarding a polio vaccination team were shot to death by motorcycle-borne assailants in Karachi, Pakistan, on Wednesday. Eight gunmen opened fire at the officers in two separate attacks in the city’s Orangi Town neighbourhood, according to senior police official Feroz Shah. They first shot three policemen in the streets of Orangi Town, and later gunned down four others who were sitting in a police mobile van a few streets away, AFP reported.

Pakistan is one of only two countries where polio remains endemic, along with Afghanistan, according to the World Health Organisation. The number of polio cases recorded in the country climbed to a 14-year high of 306 in 2014, before falling to 52 in 2015. Efforts to eradicate the crippling disease have been hindered by militant attacks on immunisation drives. The most recent attack took place in January, when a suicide bombing killed at least 14 people near a polio centre in Quetta.

Islamist groups, including the Taliban, claim that vaccination campaigns were a front for espionage or a conspiracy to sterilise Muslims. As many as 80 members of immunisation teams have been killed since December 2012.