BAGHDAD — American soldiers accidentally shot and killed the leader of a local U.S.-allied Sunni group Tuesday after coming under attack in a volatile area north of Baghdad, the military said.

The shooting comes a week before the Shiite-led Iraqi government begins to assume authority over the Sunni groups known as the Sons of Iraq, or Awakening Councils. The military has credited the Sunni revolt against al-Qaida in Iraq as a key factor in the sharp decline in violence over the past year.

The head of the group in Siniyah, Jassim al-Garrout, was killed after he rushed to the site of an ambush against U.S. forces in the area, which lies between the northern oil-hub of Beiji and Saddam Hussein's hometown of Tikrit, according to witnesses and police.

One of al-Garrout's comrades said the group would demand an apology from the Americans.

In Tuesday's incident, the U.S. soldiers were hunting for insurgents and weapons after they were hit by a roadside bomb and small-arms fire near Siniyah, according to an e-mailed military statement.

The troops then came under fire while searching a house and "shot a Sons of Iraq leader who was mistaken for the enemy when he entered the house," said Navy Lt. Cmdr. David Russell, a U.S. military spokesman in Baghdad.