The identity and condition of the pilot are not known.
Russell's role at Horizon, an Alaska Airlines affiliate where he had worked since 2015, involved towing aircraft, loading and unloading cargo and luggage, and cleaning the aircraft, officials said.
Federal agents are trying to piece together how and why an airport ramp worker stole a plane in Seattle and later died during a crash landing. An Alaska Air spokesman said he did not have information about how the incident occurred.
"It is highly fragmented", she said of the plane.
The man was in constant communication with the control tower.
The man could reportedly be heard on audio recordings telling air traffic controllers that he is "just a broken guy".
During another part of the exchange, the man said he was concerned he was going to run low on fuel.
While authorities did not release the man's name, they say the man was suicidal, and officials said Friday night the man is likely dead.
When asked if it scared her that the protocols were not able to prevent the incident, Gregoire said, "It's not fear, it's how do we get better".
"We are working background on him now", the sheriff's department tweeted. "Got a few screws loose, I guess".
Video footage on social media showed a large plane flying above the Seattle area with a F-15 fighter jet following it.
Smoke rises from the site on Ketron Island in Washington state, US, where a Horizon Air turboprop plane crashed Friday after it was stolen from Sea-Tac International Airport as seen from the air, Saturday near Steilacoom, Wash.
The Pierce County Sheriff's Office said it was "not a terrorist incident", adding the man was local and 29. The tweet said the crash may have been caused by the mechanic 'doing stunts in air or lack of flying skills'.
The US Coast Guard said it was aware of the situation happening at SeaTac Airport, NBC News reported. Petty Officer Ali Flockerzi said a 45-foot vessel was headed to the scene.
He crashed almost an hour after the plane was taken from a maintenance area, though officials said that it did not appear that the fighter jets were involved in the crash of the aircraft.