American military officials said yesterday they are investigating the videotaped fatal shooting of a wounded man by an American Marine in a mosque in Fallujah. Iraqis condemned the act as “cowardice” and “something forbidden in Islam.”

Investigators will determine whether the Marine acted in self-defense against what a spokesman described as an “enemy combatant.”

The dramatic footage was taken Saturday by pool correspondent Kevin Sites of NBC television, whose report said the man who was killed didn’t appear to be armed or threatening in any way, with no weapons visible in the mosque. The slain man was among a group of men wounded in fighting a day earlier at the mosque and left there. Three others in the group were also shot again Saturday by Marines, Mr. Sites said.

The Marine involved in the fatal shooting was withdrawn from the battlefield pending the results of the investigation, the American military said.

“We follow the law of armed conflict and hold ourselves to a high standard of accountability,” said Lieutenant General John Sattler, commanding general of the 1st Marine Expeditionary Force. “The facts of this case will be thoroughly pursued to make an informed decision and to protect the rights of all persons involved.”

The Marine statement said the investigators would look at “an allegation of the unlawful use of force in the death of an enemy combatant.”

“The purpose of this investigation is to determine whether the Marine acted in self-defense, violated military law, or failed to comply with the Law of Armed Conflict,” it said.

Florian Westphal, a spokesman for the International Committee for the Red Cross, said he couldn’t say for sure whether the men in the mosque were prisoners or not.

“The fact that was reported was that he was wounded. But whether he was already a prisoner or not was not clear to me,” Mr. Westphal said.

“We cannot, on the basis of TV images – no matter how disturbing and disconcerting they are – arrive at a judgment about an incident. We were not on the spot, so we cannot be aware of all the circumstances of this incident,” he said.

“It’s clearly recognized that people in combat situations are under enormous strain,” Mr. Westphal said

But, he added, the Geneva Conventions are clear: Protection of wounded combatants once they are out of action is a basic rule.

Iraqi Interior Minister Falah Hassan al-Nagib said that while “killing a wounded person is rejected by us,” the insurgents in Fallujah were responsible for their own brutal acts against Iraqis and foreigners, and were “killers and criminals.”

Footage of the shooting was aired on Al Jazeera television. Iraqis interviewed yesterday in Baghdad harshly condemned the killing.

“It is something forbidden in Islam, an American killed an unarmed Iraqi prisoner inside a mosque,” said Abdul-Sattar Naji.

Another Iraqi in Baghdad, Tareq Ali, called it “a criminal act” that “indicates the cowardice of the soldier who did that. The injured should be treated according to the law of wars.”

Omar Ragib of the Sunni clerical Association of Muslim Scholars said American troops “pay no heed” to the injured, the unarmed, and the sanctity of mosques.

“We saw the troops entered the mosque after they shelled it,” he said. “And we saw the effect of bombardment on the mosque walls.”

American and Iraqi commanders say gunmen frequently use mosques as refuges or fire on troops from the buildings.

The incident played out as the Marines 3rd Battalion, 1st Regiment, came to the unidentified Fallujah mosque Saturday. Mr. Sites was embedded with the unit.

A day earlier, a different Marine unit came under fire from the same mosque. Those Marines stormed the building, killing 10 men and wounding five, Mr. Sites said. The Marines said the fighters in the mosque Friday were armed with rocket-propelled grenades and AK-47 rifles. The Marines treated the wounded, he reported, left them behind, and continued on Friday with their drive to retake Fallujah.

The same five wounded men were still in the mosque on Saturday, when another Marine unit – accompanied by Mr. Sites – came to the mosque, Mr. Sites said.

On the video, as the camera moved into the mosque Saturday, a Marine can be heard shouting obscenities in the background, yelling that one of the men was only pretending to be dead.

“He’s (expletive) faking he’s dead!”

“Yeah, he’s breathing,” another Marine is heard saying.

“He’s faking he’s (expletive) dead!” the first Marine says.

The video then showed a Marine raising his rifle toward an Iraqi lying on the floor of the mosque. The video shown by NBC and provided to the network pool was blacked out at that point and did not show the bullet hitting the man. But a rifle shot could be heard.

“He’s dead now,” a Marine is heard saying. Mr. Sites reported that a Marine in the same unit had been killed a day earlier when he tended to the booby-trapped dead body of an insurgent.