Two U.S. soldiers and two unidentified attackers were killed and nine other troops injured in a firefight Tuesday in the troubled town of Fallujah (search), the U.S. military reported.

The attackers used rocket-propelled grenades and small arms, the U.S. Central Command (search) said in a statement.

Initial reports said the attackers fired from a mosque within in the city, 30 miles west of Baghdad (search).

U.S. troops responded with fire from Bradley fighting vehicles, machine guns and small arms. They killed two of the attackers and captured six, the statement said.

An Army helicopter landed during the firefight to evacuate the wounded and was damaged when a Bradley inadvertently struck it while maneuvering into a firing position.

The wounded soldiers were evacuated to a military aid station in the area.

U.S. occupying forces have run into trouble before in Fallujah, whose 200,000 people benefited greatly from Saddam Hussein's Baath regime. Saddam built chemical and other factories that employed Fallujah's young men and gave others places in his elite Republican Guard.

Protests against the Army's presence in Fallujah turned violent when U.S. soldiers fired on crowds on April 28 and April 30, killing 18 Iraqis and wounding at least 78.

The soldiers said then that they were defending themselves and the crowd fired first, but Iraqis said no shots were fired at the Americans. No Americans were wounded by gunfire.