BAGHDAD, Iraq - Insurgents dragged five Shiite Muslim schoolteachers and their driver into a classroom, lined them against a wall and gunned them down Monday.

The shooting was a rare attack on a school amid Iraq's relentless violence, and it was particularly stunning since the gunmen targeted teachers in a school where the children were mainly Sunnis. Elsewhere Monday, a suicide attack and roadside bombings killed 10 Iraqis and three Americans, bringing to at least 52 the number of people killed in the past two days.

The Iraqi and U.S. governments have warned that Sunni Arab insurgents are likely to increase their attacks ahead of the Oct. 15 national referendum.