The attack on the small Mustafa Sunni mosque began as worshippers were finishing Friday midday prayers. About 50 unarmed men, many in black uniforms and some wearing ski masks, walked through the district chanting "We are the Mahdi Army, shield of the Shiites." Fifteen minutes later, two white pickup trucks, a black BMW and a black Opel drove up to the marchers. The suspected Shiite militiamen took automatic rifles and rocket-propelled grenade launchers from the vehicles. They then blasted open the front of the mosque, dragged six worshippers outside, doused them with kerosene and set them on fire.