Story highlights Three crew members and one patient were onboard medical plane

Wreckage found several hours after the crash

(CNN) A medical transport plane crashed in northern California killing all four people onboard Friday.

Around 12:30 a.m. local time Friday, the Piper Cheyenne aircraft containing three crew members and one patient departed from airport in Crescent City, California -- about 20 miles south of Oregon.

The plane, which is part of Cal-Ore Life Flight's fleet, was headed for Oakland International Airport, located about 400 miles south.

By 1 a.m., the pilot declared an emergency indicating that there was smoke onboard, said Lt. Wayne Hanson of the Humboldt County Sheriff's Department.

Five minutes later, communication with the plane was lost, according to Cal-Ore Life Flight.

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