SEATTLE >> A 29-year-old mechanic took off in a Horizon Air Q400 turboprop at Seattle-Tacoma International Airport tonight and crashed the plane in south Puget Sound while being trailed by two fighter jets, officials said.

The plane was piloted by a Pierce County man and crashed on Ketron Island, the Pierce County Sheriff’s Office said. There appear to have been no passengers on the 76-seat plane.

The sheriff’s office said that “this is not a terrorist incident” and that the pilot was a mechanic from an unknown airline. He crashed from either doing stunts or because of a lack of flying skills.

We are aware of an incident involving an unauthorized take-off of a Horizon Air Q400. We believe there are no passengers on board. More information as we learn more.

— Alaska Airlines (@AlaskaAir) August 11, 2018

“A joyride gone terribly wrong,” Pierce County Sheriff Paul Pastor said during a news conference in Steilacoom.

Reached by phone at 9:30 p.m., Horizon Air CEO Gary Beck said it was too early to say anything and that the airline was still gathering information.

Flights from Sea-Tac were temporarily grounded but normal operations resumed about 9:30 p.m. At the Alaska Airlines terminal, it was a hushed Friday night. Lines were modest and most flights were on time.

On a live air-traffic control feed, the person flying the plane could be heard speaking with an air-traffic controller who addressed him as Rich and Richard.

An airline employee conducted an unauthorized takeoff without passengers at Sea-Tac; aircraft has crashed in south Puget Sound. Normal operations at Sea-Tac Airport have resumed.

— Sea-Tac Airport (@SeaTacAirport) August 11, 2018

At one point the person explained he had put some gas in the plane “to go check out the Olympics … and uh, yeah.”

Then later he began to worry about his fuel.

“I’m down to 2,100 (pounds),” he told the ATC. “I started at 30 something. … I don’t know what the burnage is like on takeoff, but it burned quite a bit faster than I expected.

The air-traffic controller responded calmly, seeming not to want to upset Rich as the conversation continued and he tried to coax Rich into landing somewhere.

“Oh man,” Rich immediately responded, “Those guys will rough me up if I try and land there. I think I might mess something up there too. I wouldn’t want to do that. They probably have anti-aircraft.”

“They don’t have any of that stuff,” the air-traffic controller said. “We’re just trying to find a place for you to land safely.”

“I’m not quite ready to bring it down just yet,” Rich said. “But holy smokes, I got to stop looking at the fuel because it’s going down quick.”

“Could you start a left turn and we’ll take you down to the SE, please,” the air-traffic controller then asked.

“This is probably jail time for life, huh?” said Rich. “I would hope it is for a guy like me.”

“Oh, Richard,” said the controller, “We’re not going to worry or think about that. But could you start a left turn please?”

At another point, Rich said, “I’ve got a lot of people that care about me. It’s going to disappoint them to hear that I did this. 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.”

An exchange between Rich and the controller not long before the plane crashed, perhaps the final exchange, was recorded by Aviation journalist Jon Ostrower at 8:47 p.m. and posted to his Air Current web site.

“I feel like one of my engines is going out or something,” Rich says.

“OK, Rich,” the controller responded, again very calmly. “If you could, you just want to keep that plane right over the water. Keep the aircraft nice and low.”

A witness on the ground, Bryan Sichley, said he was at Chambers Bay in Tacoma and saw a plane nose dive after being chased by two fighter jets. The Federal Aviation Administration reported about 9:30 p.m. that a plane crashed.

Royal King of Mukilteo was photographing a wedding at Lake Steilacoom when he saw a low-flying plane and two F-15 fighter jets trailing it. He knew something was off, he said Friday night.

He then saw the two jets come back around toward him, but not the plane. He didn’t hear the crash, but saw smoke.

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

He said he was shaken up by what he saw, and what he heard afterward.

“That’s somebody’s son or husband or daughter. This is a tragedy,” he said.