A huge explosion has damaged a mosque in the Iraqi flashpoint town of Fallujah. At least five people are reported killed and several others wounded. Meanwhile in Baghdad, witnesses say at least four American soldiers were seriously wounded or killed when an American military vehicle was attacked.

It is not clear what caused the explosion that rocked the al-Hassan mosque in Fallujah shortly before midnight local time. The blast centered on a small building next to the mosque.

Several witnesses said they believed the mosque was the target of a U.S. air strike, but a military spokesman told the Associated Press that the initial evidence indicates the explosion came from inside the building.

Elsewhere, a U.S. military vehicle was attacked in central Baghdad early Tuesday. An explosion destroyed the vehicle, and witnesses say a civilian car next to it was also in flames.

The blast is believed to have been caused by a rocket-propelled grenade.

Coalition forces have launched a new operation aimed at ending the daily deadly attacks on their troops, but Operation Desert Sidewinder is now in its third day and the attacks are continuing.