A "SUICIDAL" airline mechanic stole an empty Horizon Air plane from Sea-Tac International Airport and was chased by military jets before crashing into a small island.
Flights out of Sea-Tac, the largest commercial airport in the Pacific Northwest, were temporarily grounded during the drama.
"No others involved", the office of the Pierce County Sheriff said on Twitter.
Witnesses reported seeing the plane being chased by military aircraft before it crashed near Ketron Island.
The suspect was identified as a 29-year-old Pierce County resident and the sheriff's office said he was an employee "doing stunts in air or lack of flying skills".
Earlier, Alaska Airlines, the parent company of Horizon Air whose plane was stolen, tweeted a statement.
The Q400 is a twin-prop aeroplane with up to 78 seats, depending on configuration.
A Horizon Air Bombardier Dash 8 Q400, reported to be hijacked, flies over Fircrest, Washington, the US, before crashing in the South Puget Sound, August 10, 2018 in this still image taken from a video obtained from social media. "It clearly seemed immediately like there was a plane crash", he said.
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Prime Minister Justin Trudeau says his heart goes out to everyone affected by the "awful" news coming out of Fredericton. One local resident, Robert DiDiodato, told CBC that at around 7 a.m. he heard a " firecracker " type sound.
"Didn't really know it until now", the man said, according to audio from air traffic controllers.
Freakish audio from the cockpit reveals how air traffic control tried to talk him into landing the plane.
"We're working to find out everything we possibly can about what happened", he said.
Photo of apparent plane crash on Kreton Island.
The airport also confirmed the plane wasn't carrying passengers. F-15 fighter jets were sent from Portland to control the situation and, if necessary to intercept it.
"We looked across the water there's this huge fireball coming up off the west coast of Ketron Island, followed by smoke".
Witnesses filmed the moment two F-15 fighter jets began pursuing the stolen aircraft as it flew low over Seattle.
Ms Morse said her mother, who lives near the crash site, had said eight minutes later that her whole house shook.
This is a developing story and will be updated as more information becomes available.