A Horizon Air employee stole an empty plane from Sea-Tac International Airport Friday night before crashing into a small island in south Puget Sound.

FBI and National Transportation Safety Board (NTSB) officials were at the scene Saturday morning, gathering data in their investigation of the crash. An NTSB spokesperson said crews were trying to locate the flight data recorder in the debris. The plane landed upside and was “high fragmented,” according to an NTSB news conference Saturday.

No passengers or crew were onboard. The Pierce County Sheriff’s Office believes the man acted alone and the incident was not related to terrorism.

The aircraft crashed on Ketron Island in Pierce County shortly after 8:45 p.m., igniting a fire in a wooded area in the south end of the island. That fire was still burning as of Saturday morning. Firefighters remain at the scene and the fire is contained.

The man piloting the plane has not been recovered. Alaska Airlines said the aircraft involved was a 76-seat Horizon Air Q400 turboprop plane.

The man was identified as a 29-year-old Pierce County resident. Authorities initially said the man was a mechanic but Alaska Airlines later said he was believed to be a ground service agent employed by Horizon. Those employees direct aircraft for takeoff and gate approach and de-ice planes.

His motive was not clear, but the man could be heard on audio recordings telling air traffic controllers that he is “just a broken guy.”

LISTEN: Worker who stole empty plane talks with air traffic control before crash

Video showed the plane doing large loops and other dangerous maneuvers as the sun set on the Puget Sound. John Waldrop shared the following footage from Chambers Bay Golf Course:

Mark Reger was standing in his driveway near Steilacoom when he saw the planes fly overhead.

“We looked across the water there’s this huge fireball coming up off the west coast of Ketron Island, followed by smoke. There were some fire planes in the air. It clearly seemed immediately like there was a plane crash,” he said.

“It’s super scary when you think about how fast those planes are moving, the distance from Ketron Island to these houses in minuscule. It’s really scary to think what might have happened under slightly different circumstances.”

Alaska Airlines, the parent company of Horizon, released the following statement late Friday night:

“Alaska Airlines believes a ground service agent employed by Horizon Air was the individual responsible for flying the Horizon Q400 without clearance from Sea-Tac International Airport around 8 p.m. tonight. The plane, which was taken from a maintenance position and was not scheduled for passenger flight, crashed about an hour later in a wooded area on Ketron Island in rural Pierce County. No ground structures were involved at the crash site. Military jets were scrambled from Portland, but it does not appear that these jets were involved in the crash of the Horizon aircraft. This individual who took the aircraft, who has not yet been positively identified until remains are examined, is believed to have been the only person on the plane when the plane was taken from a maintenance position at Sea-Tac. First responders are at the crash site. Appropriate government agencies, including NTSB, FAA and FBI, have been notified.”

Two F-15 Air National Guard fighter jets from Portland chased down the plane while it was still in the air. The fighters did not fire on the plane and they did not appear to be involved in the crash.

An air traffic control operator attempted to guide the man to Joint-Base Lewis McChord. “We’re just trying to find a place for you to land safely,” the operator said.

“There is a runway just off to your right side in about a mile,” the controller added, referring to an airfield at Joint Base Lewis-McChord.

“Oh man. Those guys will rough me up if I try and land there,” the man responded, later adding “This is probably jail time for life, huh?”

RELATED: Witness accounts of plane stolen from Sea-Tac Airport

The plane crash ignited a fire on the south end of Ketron Island. West Pierce Fire reported a water supply issue made for a difficult firefight, but the blaze was contained to brush and did not spread to any homes.

Flights out of Sea-Tac, the largest commercial airport in the Pacific Northwest, were temporarily grounded during the drama. Some planes circled in the air or sat on the tarmac.

“They said there was some kind of emergency somewhere on the runway. After that, we just sat there for 40 minutes. But of course, everyone was just pulling out their phone and finding out what’s going on and seeing this crazy story,” said one air passenger.

White House Press Secretary Sarah Sanders said Saturday morning that President Donald Trump is “monitoring the situation.” He’s currently at his New Jersey golf club.

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

Gov. Jay Inslee thanked the Air National Guard from Washington and Oregon for scrambling jets and said in a statement “there are still a lot of unknowns surrounding tonight’s tragic incident.”

The Associated Press contributed to this report.

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