PESHAWAR, Pakistan—Gunmen shot and killed a Pakistani policeman who was providing security for polio vaccination workers in the northwest on Tuesday, according to police. The assailants fled the scene, and no one claimed responsibility for the attack in Kohat, local police official Dikdar Khan said. He added that the body of the slain policeman had been transported to a hospital. No polio workers were harmed in the attack, police said, a day after Pakistan launched a nationwide anti-polio campaign. Militants in Pakistan often target polio teams and police assigned to protect them, falsely claiming the vaccination campaigns are a Western conspiracy to sterilize children. Militants have claimed responsibility for previous attacks across the country.