Six of the Marine killed belonged to a Camp Pendleton -based squadron , the Corps says . Six Marines was assigned to a Yuma -based Marines , the Corps says . The cause of the accident remains under investigation , Marines says . The Marines were preparing to deploy to Camp Pendleton , the Corps says .
Six of the Marines killed belonged to a Camp Pendleton-based squadron , the Corps says . One Marine was assigned to a Yuma-based squadron , the Corps says . The cause of the accident remains under investigation , Marines says . The Marines were preparing to deploy to Afghanistan , the Corps says .