US troops shot dead at least 13 Iraqis demonstrating near a school overnight in Falluja, 50 km west of Baghdad, residents told Reuters on Tuesday.
Reuters correspondent Edmund Blair watched a burial in progress at a cemetery in the town. Mourners were chanting: "Our soul and our blood we will sacrifice to you martyrs."
At least one person said 17 people were killed in the shooting. Others put the death toll at between 13 and 17.
US troops had occupied the school and the unarmed demonstrators had gone there to ask them to vacate, a Sunni cleric told Reuters.