U.S. Marines say they are investigating the fatal shooting in Fallujah of an insurgent who apparently was already wounded.

The incident was videotaped by a journalist traveling with U.S. forces. Parts of the video were aired on U.S. television Monday, and showed U.S. Marines entering a Fallujah mosque and finding wounded insurgents lying on the floor. At least one of the men was still breathing, and the reporter says a Marine then shot the man at close range, although that part of the footage was not broadcast.

The reporter says troops had stormed the mosque a day earlier, killing 10 insurgents and wounding five others, including the man who was shot dead the next day.

Some information for this report provided by Reuters, AP and AFP.