The official wasn't authorized to discuss the matter and spoke on the condition of anonymity.
PCSD officials also said this is not a terrorist incident. "We're working to confirm who was on board, we believe there were no guests or crew on board other than the person operating the plane". We know who he is. Two F-15s pursued the plane but were not involved in the crash, the Pierce County Sheriff's Department said.
There was no connection to terrorism, Ed Troyer, a spokesman for the sheriff's department, said. There were no passengers aboard.
Troyer said the man who stole the plane is a mechanic at the airport. The man was a ground service agent, a job that includes directing aircraft for takeoff and gate approach, handling baggage and de-icing planes, authorities said.
Mr Southers said the man could have caused mass destruction. "He had to have been pulling some hard forces coming out of that dive", said Furois.
The married airport employee, 29, "hijacked" the Alaska Airlines plane before performing stunts in the sky as he was tailed by fighter jets today.More news: Is the US-Turkey crisis beyond repair? | USA
Alaska Airlines said no structures on the ground were damaged.
"There were some maneuvers that were done that were incredible maneuvers with the aircraft", Gary Beck, CEO of Horizon Air, said of the flight that ended with a crash onto a small island. Without confirming anything, a stolen aircraft would be a security issue.
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.
Authorities said the man was a Horizon employee for three and one-half years, had clearance to be among aircraft, and was a Horizon Air ground service agent.
Pierce County Sheriff Paul Pastor called the flight a "joyride gone horribly wrong", while also referring to Russell as "suicidal".
An air traffic controller tried to convince him to land the aeroplane.
"This is probably jail time for life, huh?" he later says, according to a recording published by The Seattle Times.More news: Seattle Airport Employee Takes Off In Stolen Plane, Crashes Nearby
The man, described by police as a 29-year-old mechanic, says that he has a lot of people that care about him.
"I would like to apologise to each and every one of them", he is heard saying in the recording. Just a broken guy. "Normal operations at Sea-Tac Airport have resumed".
The plane, which PCSD identified as belonging to Horizon Air, crashed into Ketron Island.
The crash sparked a fire in the dense forest. "In terms of improvements that we might make as a company and as an industry to make this very safe industry even safer in the future, it's too early to say". "The wings are off, the fuselage is, I think, kind of positioned upside down".
"We just need to get out there and look at the wreckage", Eckrote said at a press briefing at the Steilacoom ferry dock.
They described the man as "suicidal".
President Donald Trump was briefed on the incident and is monitoring the situation, White House Press Secretary Sarah Sanders said Saturday morning.More news: Koepka takes 2-shot lead at PGA Championship
Witnesses report F-15s chasing plane then saw smoke, and loud boom.