FALLUJAH, Iraq (CNN) -- The U.S. military is investigating an explosion early Tuesday near a mosque in the central Iraqi town of Fallujah that killed at least six Iraqis.
A military police spokesman said the blast took place in a building next to the Muslim house of worship inside the mosque compound. The building was destroyed. The mosque apparently was not seriously damaged.
Witnesses said six people were killed and four others wounded.
In video from the scene, heavy equipment could be seen removing large chunks of concrete from the rubble at the mosque site. People picked through the ruins looking for bodies.
Iraqis at the scene said a U.S. missile or bomb caused the blast, but the U.S. military said it was looking into the possibility that explosives were stored in the building.
One witness said the United States attacked the mosque: "After late prayers we heard the shaking in the mosque. We heard a helicopter overhead and a whooshing sound, and then the building was destroyed."
The military police spokesman confirmed that an explosion occurred inside the mosque compound but said no warplanes were involved.
Fallujah, a town west of Baghdad, has been a center of support for Saddam Hussein's former regime and the scene of violent encounters between Hussein loyalists and the U.S. military since April.
Also Tuesday, there were two attacks on U.S. military vehicles in the Iraqi capital.
Three soldiers were injured when a rocket-propelled grenade slammed into their Humvee near Al-Mustansiriyah University in central Baghdad, military officials said. Two of the personnel were critically wounded. The condition of the third was not known. An Iraqi interpreter died in the blast.