A single-engine plane flying through a driving rainstorm crashed into a mountain next to a refinery in Newhall early Sunday, killing all four people aboard, authorities said.
A Los Angeles County sheriff's deputy at the scene of the crash said at least two of the victims were deputies, but department spokesmen would not confirm that report Sunday night.
The names of the two men and two women on board will not be released until their families are notified, said Deputy Detta Roberts.
Roberts said the pilot appeared to be following the Antelope Valley Freeway when the Cessna 150 drifted off course in the fog and struck a mountain near the Newhall Refining Co., about a mile north of the freeway's intersection with the Golden State Freeway.
The crash was reported to the county Fire Department shortly before 1 a.m., authorities said.
Visibility at the time of the crash was estimated to have been between a quarter-mile and a half-mile, with patchy fog and heavy rain, Roberts said. The plane's origin and destination were unknown, she said.
A spokesman said that the pilot had not filed a flight plan with the Federal Aviation Administration and that the plane was not in contact with air traffic controllers at the time of the crash.
Passing motorists saw the aircraft flying over the freeway, Roberts said.
One witness, Mike Clark of Newhall, said the aircraft was flying 300 feet above the freeway with its wing lights on and appeared to be trying to land. Clark said he did not see the plane hit the mountain.
Employees of the refinery heard a loud bang when the plane slammed into the mountain about 700 feet from the refinery's outbuildings and storage tanks, Deputy Dan Cox said. The aircraft did not burst into flames.
The cause of the crash is being investigated by the National Transportation Safety Board.