Search and rescue efforts continue for the missing service members.

One Marine died and two others were seriously injured, and seven more Marines and a sailor still were missing off the California coastline after their amphibious assault vehicle sank during a training exercise on Thursday.

Out of an abundance of caution, the top general of the Marines has ordered a suspension of using AAVs until it’s determine what sank the other craft.

The incident occurred around 5:45 p.m. local time near the northwest part of San Clemente Island, the Navy-owned piece of land 80 miles off the coast of Southern California. The island is used by the Navy and Marine Corps for training.

Fifteen Marines and a sailor were aboard the AAV as it made its way back to the U.S. Navy amphibious ship USS Somerset, according to three defense officials.

The AAV was among a group of 13 AAVs returning to the ship, which was approximately a mile from shore, Lt. General Joseph Osterman, commander of I Marine Expeditionary Force, said at a press conference Friday.

Osterman said that the personnel aboard the AAV signaled to other AAVs that they were taking on water. Immediate aid provided by personnel on two other AAVs and those on a safety boat accompanying the vehicles helped rescue eight of the imperiled Marines.

“It sank completely,” said Osterman, adding that “the assumption is it went all the way to the bottom,” several hundred feet below the surface, too deep for divers.

One of the rescued Marines died later, and two others were rushed to local hospitals and last reported in critical condition. The other five who were rescued returned to the ship.

“We are continuing search-and-rescue operations at this point,” Gen. David Berger, Commandant of the Marine Corps, told reporters. “We have not moved into recovery operations. We’re still looking for them.”

AAV training on land would continue although operations on water were being suspended “out of an abundance of caution,” he added.

Multiple ships and helicopters from the Navy and Coast Guard continued combing the waters off of San Clemente Island looking for the missing service members.

The Marines were from the 15th Marine Expeditionary Unit, I Marine Expeditionary Force, that ‘s based at Camp Pendleton, north of San Diego.

AAVs are used to carry out beach landings. The small, armored craft are launched from Navy amphibious ships and convert into armored personnel carriers on land.

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

There have been 10 to 15 reported incidents over the past 20 years involving AAVs, with the most recent report involving a water-based fatality happening in January 2011.

“San Clemente is a very challenging amphibious training ground,” said Eric Oehlerich, an ABC News contributor and former Navy SEAL who’s conducted trainings there. “Night amphibious training is some of the most complex and high-risk training you can do as an amphibious soldier.”