The U.S. Marines Corps (USMC) relieved Col. Christopher J. Bronzi, commanding officer of the 15 Marine Expeditionary Unit (MEU), on Tuesday, saying it lost "trust and confidence in his ability to command" following an investigation into his unit's training accident last year.

The incident, which took place off San Clemente Island on July 30, resulted in nine dead servicemembers and has been described as the worst amphibious assault vehicle (AAV) accident in Marine history.

Before July's accident, only eight marines had died in AAV-related incidents, the Marine Corps Times reported.

The Marines said Lt. Gen. Steven Rudder replaced Bronzi with Col. Fridrik Fridriksson, who previously commanded 11th MEU, as commanding officer of the 15th MEU.

MARINES IN TRAINING EXERCISE ACCIDENT OFF CALIFORNIA COAST ID'D

Tuesday's announcement came at the end of an eight-month process of compiling the report on the incident. An AAV carrying 16 individuals from San Clemente Island was overtaken by water and sank about a half a mile out to sea, according to the Orange County Register.

U.S. flag-draped coffins containing the remains of seven U.S. Marines and a Navy sailor recovered off the coast of San Clemente Island following a training accident are pictured at Marine Corps Air Station Miramar, Calif., before a transfer to Dover Air Force Base, Del., in this Aug. 12, 2020, handout photo supplied by the U.S. Marines. (Lance Cpl. Brendan Mullin/U.S. Marine Corps/Handout via REUTERS)

U.S. flag-draped coffins containing the remains of seven U.S. Marines and a Navy sailor recovered off the coast of San Clemente Island following a training accident are pictured at Marine Corps Air Station Miramar, Calif., before a transfer to Dover Air Force Base, Del., in this Aug. 12, 2020, handout photo supplied by the U.S. Marines. (Lance Cpl. Brendan Mullin/U.S. Marine Corps/Handout via REUTERS) (Lance Cpl. Brendan Mullin/U.S. Marine Corps/Handout via REUTERS)

One of the marines, 19-year-old Lance Cpl. Guillermo S. Perez, was pronounced dead on the scene while seven others and a Navy corpsman were later recovered when the vehicle was found on the ocean floor.

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"We are deeply saddened by this tragic incident, Bronzi said in a press release in August. "I ask that you keep our Marines, Sailors, and their families in your prayers as we continue our search."

At the conclusion of the search and rescue effort, Bronzi added, "[t]he steadfast dedication of the Marines, Sailors, and Coast Guardsmen to the persistent rescue effort was tremendous."

Fox News' Lucas Tomlinson contributed to this report.