Iraqi police say an airstrike by U.S. helicopters on Baghdad's Sadr City district has killed six people and wounded 19.
Police say two of those killed in the strike late Wednesday were brothers aged seven and nine. They spoke on condition of anonymity because they were not authorized to speak to the media.
The U.S. military has confirmed its forces fired two Hellfire missiles at gunmen who were firing at U.S. troops. It said the four killed were among the attackers.