Navy and Coast Guard officials decided to end the search effort after 40 hours.
"It is with a heavy heart that I decided to conclude the search and rescue effort,'' said Col. Christopher Bronzi, the commanding officer of the 15th Marine Expeditionary Unit (MEU). "As we turn to recovery operations we will continue our exhaustive search for our missing Marines and sailor.''
RELATED: IE family of 2 young Marines mourning after deadly training accident
All of the victims' next-of-kin have been notified.
On Sunday night, officials with the 15th MEU, I Marine Expeditionary Force (MEF), identified the Marine who was killed and seven Marines and one sailor who are presumed dead after the accident.
Lance Cpl. Guillermo S. Perez, 20, of New Braunfels, Texas was pronounced dead at the scene before being transported by helicopter to Scripps Memorial Hospital in San Diego. He was a rifleman with Bravo Company, Battalion Landing Team (BLT) 1/4.
RELATED: 1 Marine killed, 8 missing after amphibious vehicle accident off coast of San Clemente Island, officials say
Officials said the presumed dead are:
Pfc. Bryan J. Baltierra, 19, of Corona, a rifleman with Bravo Company, BLT 1/4.
Lance Cpl. Marco A. Barranco, 21, of Montebello, a rifleman with Bravo Company, BLT 1/4.
Pfc. Evan A. Bath, 19, of Oak Creek, Wis., a rifleman with Bravo Company, BLT 1/4.
U.S. Navy Hospitalman Christopher Gnem, 22, of Stockton, a hospital corpsman with Bravo Company, BLT 1/4.
Pfc. Jack Ryan Ostrovsky, 21, of Bend, Ore. a rifleman with Bravo Company, BLT 1/4.
Cpl. Wesley A. Rodd, 23, of Harris, Texas, a rifleman with Bravo Company, BLT 1/4.
Lance Cpl. Chase D. Sweetwood, 19, of Portland, Ore., a rifleman with Bravo Company, BLT 1/4.
Cpl. Cesar A. Villanueva, 21, of Riverside, a rifleman with Bravo Company, BLT 1/4.
Officials said a Marine rifleman with Bravo Company, BLT 1/4 was injured. The Marine was transported from the scene to Scripps Memorial Hospital by helicopter and was in critical condition.
Officials also said a Marine AAV crewmember with Mechanized Co., BLT 1/4 was transported from the scene to Scripps Memorial Hospital by helicopter and was in critical condition. He has since been upgraded to stable condition.
There were 15 Marines and a Navy sailor in the vehicle around 5:45 p.m. Thursday when it started taking on water as it traveled from the shores of San Clemente Island to a Navy ship, said Lt. Cameron H. Edinburgh, a Marine Corps spokesman for Camp Pendleton, said at a Friday afternoon news conference.
Seven of the personnel were able to get out of the sinking land and sea-going vehicle and were pulled from the water.
The other rescued Marines received clean bills of health and returned to their units, officials said.
Crews aboard the USS John Finn, USS Makin Island, USS Somerset and USS San Diego, assisted in the operation. Eleven U.S. Navy helicopters, several smaller USN and Marine Corp. vessels, a U.S. Coast Guard cutter and a chopper from USCG Sector San Diego, also participated in the search for the missing service personnel.
The 26-ton amphibious vehicle went down more than 1,000 yards from a beach on the northwest side of the San Clemente Island in water several hundred feet deep, Osterman said.
"It's really below the depth that a diver can go to,'' Osterman told reporters.
The incident will be the subject of an exhaustive investigation, according to USMC officials.
"Our thoughts and prayers have been, and will continue to be with our Marines' and sailor's families during this difficult time,'' Bronzi said. "The steadfast dedication of the Marines, sailors, and Coast Guardsmen to the persistent rescue effort was tremendous.''
All of the Marines involved were assigned to the 15th Marine Expeditionary Unit, based out of Camp Pendleton.
The Undersea Rescue Command will now deploy an underwater drone to look for remains on the ocean floor, with support from offshore supply ship HOS Dominator.
San Clemente Island is one of the eight islands that make up the Channel Islands archipelago. The island is owned and operated by the U.S. Navy and is part of Los Angeles County. It is administered by Naval Base Coronado.
Thursday's accident marks the third time in less than a decade that Camp Pendleton Marines have been injured or died in amphibious assault vehicles during training exercises.
In 2017, 14 Marines and one Navy sailor were hospitalized after their vehicle hit a natural gas line, igniting a fire that engulfed the landing craft during a training exercise at Camp Pendleton, the sprawling coastal Marine Corps base north of San Diego.
And in 2011, a Marine died when an amphibious assault vehicle in a training exercise sank off the shores of Camp Pendleton.
The Marines use the vehicles to transport troops and their equipment from Navy ships to land. They are nicknamed "amtracs" because the original name for the vehicle was "amphibious tractor."
“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, 15th MEU Commanding Officer.— I MEF (@1stMEF) July 31, 2020
The armored vehicles outfitted with machine guns and grenade launchers look like tanks as they roll ashore for beach attacks, with Marines pouring out of them to take up positions.
The I Marine Expeditionary Force is a Marine Air Ground Task Force whose mission is "generating, deploying, and employing ready forces and formations for crisis response, forward presence, major combat operations, and campaigns."
City News Service contributed to this report.