Four US Marines have been killed in an accident on a training ground at the Camp Pendleton base near San Diego, California.
The marines died while clearing the area of obstructions, said Marines spokesman Lieutenant Ryan Finnegan. The cause of the accident is under investigation.
He could not confirm an NBC News report that the incident involved the detonation of unexploded ordnance, but did say the type of operation the marines were on could involve ordnance disposal.
“We offer our heartfelt prayers and condolences to the families of the Marines lost today in this tragic accident,” Brigadier General John W Bullard, the base commander.