Two policemen were killed in a gun attack in Mardan s Rustam tehsil on Wednesday, the police said. They were returning after security duty with a team of anti-polio vaccinators, according to the police. The deceased policemen were identified as Syed Ali Raza and Shakir. A heavy contingent of police reached the site. The area was cordoned off and a search was on for the perpetrators. In January, a policeman was killed in attack targeting anti-polio vaccinators in Karak. The vaccinators remained unhurt in the attack. Pakistan is one of only two countries where polio remains endemic. Attempts to stamp it out have been badly hit by opposition from militants and attacks on i.