Police at the scene say they were attacked from all sides with mortar fire, assault-rifle fire, and rocket-propelled grenades. The assault happened in Bohruz, 45 kilometers north of Baghdad.
Meanwhile, a U.S. soldier was killed south of the capital. The U.S. military says the soldier died of non-combat-related causes.
In other developments, a U.S. military official says the United States plans to keep about 160,000 American troops in Iraq at least through Iraq's 15 December national elections.
Lieutenant General James Conway told reporters in Washington that commanders expect to generally maintain the current troop levels through the vote for a new Iraqi national assembly.