A US air raid in Baghdad today killed at least eight people, medical sources said.
A medical source said eight bodies were brought in from a southern neighbourhood after US helicopters targeted a building. A police source put the death toll at 10, saying many were believed to be civilians.
It is the second time this week that US forces have been accused of killing civilians in air strikes. US forces are investigating an attack in southern Iraq this week that local police said killed five women and four children.
Elsewhere, the Iraqi army said it had killed 30 suspected al-Qaeda insurgents north of the capital.
In Washington, a military spokeswoman said the first US military unit scheduled to withdraw from Iraq under President George W Bush's plan to cut troop levels had left the war zone.
The 13th Marine Expeditionary Unit, a group of 2,200 marines who were stationed in western Anbar province, had boarded a naval vessel and begun its trip home.