What we know so far

- Man who stole plane said he was a 'broken guy'

- A plane was stolen from Seattle Airport and crashed

- No passengers were aboard

- Witnesses reported seeing the plane being chased by military aircraft

- The man is a 29-year-old airline mechanic

- Sheriff's officials say the man was "suicidal" and there is no connection to terrorism.

- A background investigation on the man is underway

- The plane was a Horizon Air Q400

-The Q400 is a turboprop aircraft with 76 seats.

SEATAC, Wash — A "suicidal" airline mechanic stole an empty Alaska Airlines plane and took off from Sea-Tac International Airport in Washington state before crashing near a small island Friday night, officials said.

Preliminary information suggests that the 29-year-old mechanic stole the Horizon Air Q400 and the crash occurred because the person was "doing stunts in air or lack of flying skills," the Pierce County Sheriff's Department said.

Witnesses reported seeing the plane being chased by military aircraft before it crashed near Ketron Island, southwest of Tacoma, Washington. There were no passengers aboard.

Ed Troyer, a spokesman for the Pierce County Sheriff's Department, said on Twitter that the man was suicidal and there was no connection to terrorism.

The sheriff's department said they were working to conduct a background investigation on the man, whose name was not immediately released.

The man could be heard on audio recordings telling air traffic controllers that he is "just a broken guy."The US Coast Guard was sending a 45-foot (14-meter) vessel to the crash scene after witnesses reported seeing a large plume of smoke in the air, Petty Officer Ali Flockerzi said.

Horizon Air is part of Alaska Air Group and flies shorter routes throughout the US West. The Q400 is a turboprop aircraft with 76 seats.

Spokesmen for the Transportation Security Administration, the US Department of Homeland Security and the Federal Aviation Administration directed inquiries to local authorities.

A look back at the accident (all times local)

11:10 pm

An airline mechanic who stole a Horizon Air plane from a Seattle airport told air traffic controllers that he was a "broken guy" but also joked about whether the airline would hire him as a pilot if he landed safely.

The man, who was addressed as "Rich" in audio recordings with air traffic controllers, said he didn't want to land at a nearby military base.

He told them, "Those guys will rough me up if I try and land there." During another part of the exchange, the man said he was concerned he was going to run low on fuel.

Later, he said he's "got a lot of people that care about me." He said he didn't want to disappoint them but that he was "just a broken guy, got a dew screws loose, I guess."

10:15 pm

Sheriff's officials say a man who stole an Alaska Airlines plane from an airport in Washington state was "suicidal" and there is no connection to terrorism.

Ed Troyer, a spokesman for the Pierce County Sheriff's Department, says on Twitter Friday night that a 29-year-old airline mechanic stole the Horizon Air Q400 from Sea-Tac International Airport.

Witnesses reported seeing the plane being chased by military aircraft before it crashed near Ketron Island. There were no passengers aboard.

The sheriff's department said they were working to conduct a background investigation on the man, whose name was not immediately released.

The man could be heard on audio recordings telling air traffic controllers that he's "got a lot of people that care about me" and that he is "just a broken guy."

9:50 pm

Officials at Sea-Tac International Airport say an Alaska Airlines plane that was stolen by an airline employee and has crashed in Washington state.

Airport officials say in a tweet Friday night that an airline employee "conducted an unauthorized takeoff without passengers."Witnesses reported seeing the plane being chased by military aircraft near the airport.

The Pierce County Sheriff's Office said on Twitter that preliminary information suggested that a mechanic had stolen the aircraft. The tweet said the crash may have been caused by the mechanic "doing stunts in air or lack of flying skills."A Coast Guard spokeswoman said the agency was responding to a report of a smoke plume and possible plane crash. Petty Officer Ali Flockerzi said a 45-foot vessel was headed to the scene.

9:37 pm

Alaska Airlines says there was an "unauthorized take-off" of an airplane and witnesses reported a jet being chased by military planes near Sea-Tac International Airport in Washington state.

The airline tells The Associated Press that the plane was a Horizon Air Q400 and it believed no passengers were on board.

No other information was immediately available.

Horizon Air is part of Alaska Air Group and flies shorter routes throughout the US West.

The Q400 is a turboprop aircraft with 76 seats.