All the marines involved were assigned to the 15th Marine Expeditionary Unit, which is based at Camp Pendleton, the largest US Marine base on the West Coast of the United States, between Orange and San Diego counties. Fifteen Marines and one sailor were inside the vehicle at the time of the incident, and eight people have been recovered. "I ask that you keep our Marines, sailors and their families in your prayers as we continue our search", Col. Christopher J. Bronzi, 15th MEU Commanding Officer, said in a statement.
Amphibious Assault Vehicles ( AAVP-7A1) are tracked armored transport for Marines that can move on land or water. One of the eight Marines who were rescued died at a San Diego hospital.
"Representatives have notified all families of the Marines and Sailor involved in Thursday's tragedy", the Marines said early Friday "We have covered more than 200 square nautical miles in the extensive search for our 8 missing service members".
Officials at Camp Pendleton in southern California said that one of eight Marines rescued in the mishap off the shore of San Clemente Island was declared dead after being taken to hospital and two more remained in intensive care. All are assigned to the 15th Marine Expeditionary Unit.
The Navy and Coast Guard were discussing ways to reach the sunken vehicle to get a view inside it, Lt. Gen. Osterman said.
The Marines who were aboard the vehicle when it sank were wearing their normal combat gear, which includes body armor, because of the training that they were doing on the island.
Other assault vehicles quickly responded but couldn't stop the 26-ton, tank-like vehicle from quickly sinking, Osterman said.
Osterman noted that with half of the personnel recovered so far, the members aboard were able to egress and that their flotation devices had worked. Search and rescue efforts are still underway with support from the Navy and Coast Guard'.
And in 2011, a Marine died when an amphibious assault vehicle in a training exercise sank off the shores of Camp Pendleton.
According to the Marines website, the Expeditionary Force is a "combined arms force consisting of ground, air and logistic forces".