SEATAC, Washington (AFP) -- A 29-year-old "suicidal" airport worker who commandeered an empty plane from Seattle's main airport and took it on an hour-long flight chased by F-15 fighter jets before crashing into a small island did not commit any security violations, officials said Saturday.

Horizon Air employee Richard Russell told an air traffic controller he was "just a broken man" minutes before dying late Friday in the Bombardier Q400 twin-engine turboprop plane, appearing to apologize for his actions. Law enforcement officials identified him to US media.

Authorities ruled out any link to terror. Russell "had access legitimately" to the plane, said Mike Ehl, director of aviation operations at the airport in the northwestern US state of Washington, adding that "no security violations were committed."

Video taken by a bystander showed the 76-seat plane making a big, slow loop-the-loop as US Air Force F-15 jets gave chase, then flying low over Puget Sound before crashing into sparsely populated Ketron Island, setting trees on fire.

"To our knowledge, he didn't have a pilot's license," Gary Beck, CEO of Alaska Airlines affiliate Horizon, told reporters.

"Commercial aircraft are complex machines... No idea how he achieved that experience."

But Russell's role at Horizon, where he had worked since 2015, involved towing aircraft as part of a two person team, in addition to loading and unloading cargo and luggage and cleaning the aircraft, according to Beck.

"At this time, we believe he was the only one in the aircraft but of course, we haven't confirmed that at the crash site," said Jay Tabb, chief of the FBI's Seattle division.

- Joyrider or suicidal? -

Ruling out a terror link, Pierce County Sheriff Paul Pastor noted that "most terrorists don't do loops over the water... This might have been a joyride gone terribly wrong."

Ed Troyer, of the sheriff's office, described Russell as "suicidal."

Russell lived locally and had acted alone. Initial information had said he was an airline mechanic.

Recently retired airline operational supervisor Rick Christenson said he and Russell's other former colleagues were "stunned."

"He was a quiet guy. It seemed like he was well liked by the other workers," Christenson told The Seattle Times. "I feel really bad for Richard and for his family. I hope they can make it through this."

The plane was stolen around 8:00 pm (0300 GMT Saturday) and crashed 90 minutes later, officials said.

The sheriff's office said the F-15s arrived minutes after the plane was stolen and kept the aircraft "out of harm's way and people on the ground safe."

The fighter jets flew at supersonic speed, triggering a boom first taken to be an explosion, as they raced to intercept the plane.

The plane is believed to have flown as low as 100 feet (30 meters) above the water at one point

President Donald Trump was briefed and the White House praised authorities' quick response to the crisis.

- 'Broken guy' -

John Waldron, who captured the plane's loop-the-loop on video, told CNN he was out for an evening stroll and initially thought the aircraft were practicing for an air show.

Map of the location of the crash

He estimated that the plane, at its lowest point, was no more than 100 feet (30 meters) above the water.

As Russell nosedived toward the water, "We were all screaming, 'Oh my god, oh my god!' and I was yelling, 'Pull up, pull up!'" Christenson said.

In a conversation with the control tower, the pilot came across as excitable, confused and even apologetic.

"Congratulations, you did it," the control tower tells him, according to an audio feed aired on CNN.

"Let's turn around the air and land it and not hurt anybody on the ground."

Eyewitnesses said the plane's acrobatics made them believe at first that it was an air show

"I don't know, man," the pilot answers. "I don't want to. I was kind of hoping that was going to be it, you know."

During the conversation, the man says he had put some fuel in the plane "to go check out the Olympics" -- the Olympic Mountains that lie about 100 miles (160 kilometers) away.

But he later worried he was running low, saying the fuel had burned "quite a bit faster than I expected."

The control tower then urged him to land at a nearby military base.

"I wouldn't want to do that. They probably have anti-aircraft," he responds.

"This is probably jail time for life, huh?" he later says, according to a recording published by The Seattle Times.

"I've got a lot of people that care about me. It's going to disappoint them to hear that I did this," he said.

"I would like to apologize to each and every one of them. Just a broken guy, got a few screws loose, I guess. Never really knew it until now."