A U.S. Marine Corps F/A-18 Hornet jet crashed early Friday morning during a training flight near Marine Corps Air Station Miramar in San Diego.

According to military officials, the cause of the crash is currently under investigation.

Authorities say the fighter jet went down close to Interstate 15 near the military base. Search and rescue efforts are ongoing.

Officials have not yet provided details on the pilot’s condition or indicated if any other personnel were onboard the aircraft.

The F/A-18 Hornet is an all-weather fighter and attack jet described as the “workhorse” of Marine Corps aviation. It has been the Marines’ primary strike and air superiority aircraft for decades.