"At approximately 8am (0500 GMT) on 21 February, three US soldiers were killed and eight were wounded when an IED (improvised explosive device) detonated during a medical evacuation of a soldier," a statement said on Monday.
"The soldier was injured in a convoy accident caused by a civilian vehicle," it added, without specifying where the attack took place.
The death brings to 1482 the number of US military personnel killed in Iraq since the US-led war in March 2003.
In other developments, armed fighters in Iraq seized a female Iraqi television presenter in the northern city of Mosul, an official from her local television network said.
The two Indonesian journalists
were released on Monday
The news of Raida Muhammad Wajih Wazan's capture came the same day that two Indonesian journalists were released.
Wazan, who works for a branch of the local station Iraqiya, was taken by several masked armed men on Sunday night while she was returning to her house in Mosul's al-Shahwan neighbourhood, an official said on Monday.
No other details were immediately available.
Last Wednesday, half a dozen mortar rounds were fired at the Mosul TV station, wounding three technicians working there.
In the city of Baquba, armed fighters killed a truck's driver and set ablaze three trucks carrying supplies to the Iraqi army. In the city of Hiyt, two US military vehicles were destroyed by rocket-propelled grenades.
In another town - Haditha - US warplanes bombed government buildings including a municipality office following clashes between US forces and armed fighters.
In the city of Siwara, Aljazeera has learned that Iraqi police found eight bodies in the Tigris river which are thought to be of truck drivers kidnapped days ago.