Fifteen Marines and the sailor were participating in a routine training exercise off the coast of San Clemente Island on Thursday when their amphibious assault vehicle began taking on water and sank. Eight Marines were pulled from the water – one died and two others remained hospitalized in critical condition Sunday, the Marines said in a statement.Marine Corps, Navy and Coast Guard helicopters and ships searched more than I,000 square nautical miles for 40 hours. Search team commanders ultimately determined there was little probability of a successful rescue given the circumstances of the incident, the statement said.“It is with a heavy heart, that I decided to conclude the search and rescue effort,” said Col. Christopher Bronzi. “The steadfast dedication of the Marines, sailors. and Coast Guardsmen to the persistent rescue effort was tremendous.”The vehicle sank in several hundred feet of water off San Clemente Island, about 60 miles off the coast of Camp Pendleton in San Diego County.