LOS ANGELES (AP) _ A 1964 California plane crash possibly caused by gunfire killed 44 people aboard an airliner flying from Stockton to San Francisco.

The crash of a twin-engine turboprop on May 7, 1964, near Concord occurred after a Pacific Airlines pilot was heard by the Oakland Airport control tower screaming on his radio, ''I'm shot, I'm shot 3/8 Oh my God, help 3/8''

An FBI investigation later found that Frank Gonzalez, 27, of San Francisco, a member of the Philippine yachting team at the 1960 Olympics, had taken out a flight insurance policy of $100,000 before boarding the flight and the day before had purchased a .357-caliber magnum Smith & Wesson revolver.

Although the cause of the crash was not determined, the revolver was found in the plane's wreckage with six empty cartridges and showed evidence of being recently fired.

On Monday, a Pacific Southwest Airlines plane crashed in San Luis Obispo County, killing 43 people. Just before the crash, the pilot radioed he had an emergency.

Gene Katz, a pilot of a small plane heading from Santa Rosa to Los Angeles, said he overheard the airliner pilot of the doomed plane talking with air traffic controllers.

''The PSA pilot ... said he had an emergency, there was gunfire, and he was squawking in 'Seven-seven-zero-zero,' which is a special code,'' Katz said. ''At that time, the controller said: 'Say again,' and the captain confirmed, he said, 'I have an emergency, gunfire,' and that was the last communication.''

Drucella Andersen, a spokeswoman for the National Transportation Safety Board, confirmed that the crew had reported hearing gunshots in the back of the plane. Whether any shots were fired on the plane was under investigation.