A large search effort just outside a military base in San Diego on Johnathan WalkerFriday discovered the body of a U.S. Marine Corps fighter pilot, authorities say.

"With a heavy heart, our condolences go to the Marine's family during this time," said a statement from the 2nd Marine Aircraft Wing in North Carolina.

The pilot, who was the only person onboard, was not immediately identified. According the statement, the identities of service members are not released until 24 hours after their family has been notified.

Late Thursday, just before midnight, a F/A-18 Hornet crashed on government property east of the Marine Corps Air Station Miramar, according to a base news release. The fighter jet belonged to the Marine All-Weather Fighter Attack Squadron.

The cause of the crash remains unknown, military officials said. An investigation into the incident is ongoing.

The F/A-18 Hornet is the first all-weather fighter and attack aircraft, according to the U.S. Navy Office of Information. It was designed "for traditional strike applications" and was used extensively during Operation Desert Storm. The supersonic fighter jet has been described as the "the workhorse of Marine Corps tactical aviation."