Two Iraqi men were killed and two U.S. servicemen injured in an exchange of gunfire at a mosque in Baghdad (search), witnesses and soldiers said.

But the U.S. Central Command (searchsaid Monday it could not confirm that the incident took place or that there were casualties.

However, witnesses said that in an apparently coordinated attack on Sunday, a grenade was thrown at the turret of an armored vehicle as unidentified gunmen opened fired from the rooftops of buildings opposite the Abu Hanifa mosque.

The mosque is in the Adamiya district (search), one of the last areas of Baghdad to fall to coalition forces during the war.

"We have evidently had some type of explosive thrown at one of our vehicles and injured some personnel. Two personnel that we know of," Sgt. Larry Caldwell told Associated Press Television News.

Iraqis at the scene said that two civilians were killed in the exchange of fire that ensued.

Dozens of U.S. troops have been killed and injured in a series of hit-and-run attacks that have become common since the end of major combat last month.