Six policemen were killed and several others injured when militants attacked a police station in Dera Ismail Khan, sources said on Saturday. Police sources said about 10 to 12 militants wearing suicide vests stormed the City police station in Kolachi Tesheel with heavy weaponry. They said 25 police officials were held hostages in the police station. The area was reverberating with heavy gunfire and blasts. Heavy contingent of security forces and police rushed to the spot and cordoned off the police station. Local people told media that suspect men and a woman were seen entering in the police station before the attack.