CAMP PENDLETON (CBS SF/CNN) — A desperate search was under way early Friday for eight Marines who were missing after a training accident involving an amphibious vehicle off the coast of Southern California left one dead and two others hospitalized.

The search effort was being undertaken by the Navy and Coast Guard in the waters off San Clemente Island, according to a news release from the US Marine Corps 1st Expeditionary Force.

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The incident occurred during a 15th Marine Expeditionary Unit and Makin Island Amphibious Ready Group routine training exercise around 5:45 p.m. Thursday.

The Marines were in an amphibious assault vehicle, or AAV, and reported they were taking on water. Sixteen people were inside the vehicle at the time of the accident. Eight people were rescued.

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All of the service members in the incident are assigned to the 15th MEU based out of Camp Pendleton.

“We are deeply saddened by this tragic incident,” said Col. Christopher Bronzi, the commanding officer of the 15th MEU. “I ask that you keep our Marines, Sailors, and their families in your prayers as we continue our search.”

The name of the Marine killed will be withheld until 24 hours after next of kin have been notified. The incident is under investigation.

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