A police constable was killed and four others wounded on Monday when militants opened fire on a security escort accompanying polio vaccination teams in Hangu district (a restive area of Khyber Pakhtunkhwa province in northwestern Pakistan). The attack occurred on the first day of a nationwide vaccination campaign running from April 13 to 19, with police saying two attackers were also killed in retaliatory fire. Pakistan is one of only two countries, alongside Afghanistan, where polio remains endemic, and security personnel escorting vaccination teams are frequently targeted by militants, with official data recording 96 people killed in such attacks in Khyber Pakhtunkhwa alone since 2012.