An airline employee at Seattle's Sea-Tac International Airport crashed an airplane after an "unauthorized takeoff" late Friday night, the airport confirmed on social media.

Two military F-15s chased the plane but were not involved in the crash, according to the Pierce County (Washington) Sheriff's department and the Associated Press. The plane crashed into Ketron Island, about 30 miles south of the airport, with no passengers onboard, airport officials said. 

The pilot was a suicidal 29-year-old male and a resident of Pierce County, whose name was not immediately released, according to Ed Troyer, the county's public information officer. 

The FBI's Seattle office issued a statement early Saturday, saying that the investigation is still ongoing and that the information gathered does "not suggest a terrorist threat or additional, pending criminal activity."

Alaska Airlines later confirmed that a Horizon Air Q400, a turboprop aircraft with 76 seats, made an "unauthorized takeoff" from SeaTac airport. Horizon Air is part of Alaska Air Group and flies shorter routes throughout the U.S. West.

"We believe it was taken by a single Horizon Air employee and that no other passengers or crew were onboard," Horizon Air Chief Operating Officer Constance von Muehlen said in a statement. "Our hearts are with the family of the individual aboard as well as all of our Alaska Air and Horizon Air employees."

The plane "was doing stunts in air or lack of flying skills caused crash into Island," the department tweeted. Video showed the aircraft doing large loops and other dangerous maneuvers as the sun was about to set.

Ketron Island, in the Seattle metro area, is part of Pierce County. The county is also home to Mount Rainier, the tallest mountain and volcano in the Cascade Range. 

A Coast Guard spokeswoman said the agency was responding to a report of a smoke plume and possible plane crash, according to the AP. Petty Officer Ali Flockerzi said a 45-foot vessel was headed to the scene.

Royal King to the Seattle Times that he was photographing a wedding when he saw a plan and two F-15 fighter jets trailing it. He said he didn’t see the crash but saw smoke.

“It was unfathomable, it was something out of a movie,” King told the Times. "The smoke lingered. You could still hear the F-15s, which were flying low."

In a statement, Washington Gov. Jay Inslee thanked the responding fighter pilots that flew alongside the stolen aircraft.

"I want to thank the Air National Guard from Washington and Oregon for scrambling jets to keep Washingtonians safe," Inslee tweeted, adding: "Those pilots are trained for moments like tonight and showed they are ready and capable."

Contributing: Emily Brown, USA TODAY; KING-TV, Seattle; Associated Press

Read or Share this story: https://usat.ly/2ns8z8P