Search crews safely recovered two Marines from an F-18 fighter jet that went down in the Pacific Ocean off the California coast near San Diego, the US Coast Guard confirmed to NewsCore on Thursday.

It was not known what caused the Marine Corps jet to go down and an investigation had been launched, the Coast Guard said. The two Marines were taken to the hospital, but their condition was not immediately known.

The jet went missing at about 10:30pm local time Wednesday about 70 miles (110 kilometers) south of San Diego and 40 miles (65 kilometers) west of Ensenada, Mexico.

The F-18 was flying on a mission from Marine Corps Air Station Miramar with another plane when one pilot lost contact with the other.

The second pilot radioed for help and reported seeing debris in the water, the Coast Guard said.

Two Coast Guard cutters, a C-130 airplane, a 110-foot patrol boat and a navy helicopter were deployed in the search late Wednesday.