Iraqi officials said the gunmen who attacked the provincial headquarters in the Shiite holy city of Karbala, killing five other U.S. troops on Saturday, were wearing military uniforms and drove up in black sport utility vehicles commonly used by foreign dignitaries — an apparent attempt to impersonate Americans.

The local governor said the gunmen stormed into the building during a U.S.-Iraqi meeting to discuss security measures ahead of the Shiite Ashoura festival.

In the Karbala incident, provincial Gov. Akeel al-Khazaali, who was not at the security meeting, said the SUVs were able to get through a checkpoint on the outskirts of the city, 50 miles south of Baghdad, because police assumed it was a diplomatic convoy and informed headquarters that it was coming.

"The group used percussion bombs and broke into the building, killed five Americans and kidnapped two others, then fled to the area near Mussayib," about 20 kilometers to the north, the governor said, adding that Iraqi troops later found one of the SUVs with the three dead bodies dressed in military uniforms.

The U.S. military, which has said that five U.S. soldiers were killed and three were wounded while repelling the attack, denied that two U.S. troops were kidnapped.

"Nothing has changed since the night before," Lt. Col. Christopher Garver said. "During the attack on our coalition forces, we sustained five U.S. KIA and three US wounded. All of MND-Baghdad [multinational division] personnel were accounted for after the action."

A security official in Karbala, speaking on condition of anonymity because he was not authorized to disclose the information to the media, also said the gunmen who carried out the attack on the Provincial Joint Coordination Center were using SUVs similar to ones used by the U.S. authorities. He said during their attack, the gunmen used stun grenades then left shortly afterward.

The official said the convoy of gunmen then into Babil province. The police commander in the province confirmed that they entered the region before disappearing.

Although Babil province is predominantly Shiite, some parts of it, just south of Baghdad, are Sunni and insurgents are known to be active there.