The theft of an empty plane by an airline worker who performed dangerous loops before crashing into a remote island in Puget Sound illustrated what aviation experts have long known: One of the biggest potential perils for commercial air travel is airline or airport employees causing mayhem.
"The greatest threat we have to aviation is the insider threat," said Erroll Southers, a former FBI agent and transportation security expert.
"Here we have an employee who was vetted to the level to have access to the aircraft and had a skill set proficient enough to take off with that plane."
Video showed the Horizon Air Q400, a turboprop plane that seats 76 people, doing large loops and other dangerous maneuvers as the sun set on Puget Sound.
The flight lasted about 75 minutes, and ended when he crashed into the small island after being chased by military jets. The two F-15C aircraft scrambled from Portland didn't fire the plane, authorities said.
Mr Southers said the man could have caused mass destruction.
"If he had the skill set to do loops with a plane like this, he certainly had the capacity to fly it into a building and kill people on the ground," he said.
A US official briefed on the matter told The Associated Press the man was Richard Russell. The official wasn't authorized to discuss the matter and spoke on the condition of anonymity.
He is presumed to have died in the crash.
Officials said he was a 3.5-year Horizon employee and had clearance to be among aircraft, but that to their knowledge, he wasn't a licensed pilot. He took the empty plane from a maintenance area.
It's unclear how Mr Russell attained the skills to do loops in the aircraft, authorities said. Ground service agents direct aircraft for takeoff and gate approach and de-ice planes, as well as handle baggage.
Gary Beck, CEO of Horizon Air, said it wasn't clear how the man knew to start the engine, which requires a series of switches and levers.
At a news conference, officials from Alaska Airlines and Horizon Air said that they are working with authorities.
"Last night's event is going to push us to learn what we can from this tragedy so that we can ensure this does not happen again at Alaska Air Group or at any other airline," said Brad Tilden, CEO of Alaska Airlines.
Investigators expect they will be able to recover both the cockpit voice recorder and the event data recorder from the plane.
Mr Russell could be heard on audio recordings talking to air traffic controllers, who tried to convince him to land the airplane.
"There is a runway just off to your right side in about a mile," the controller says, referring to an airfield at Joint Base Lewis-McChord.
"Oh man. Those guys will rough me up if I try and land there," Mr Russell responded, later adding, "This is probably jail time for life, huh?"
Later. Mr Russell said: "I've got a lot of people that care about me. It's going to disappoint them to hear that I did this ... Just a broken guy, got a few screws loose, I guess."
Mr Russell's family said in a statement that they are stunned and heartbroken.
They referenced the recordings and said and that it's clear Mr Russell, who went by the nickname "Beebo," didn't intend to harm anyone and "he was right in saying that there are so many people who loved him."
An explosion in northern Syria killed at least 36 people on Sunday (Monday NZ Time) and wounded many others, but the cause of the blast wasn't immediately known, opposition activists said.
The opposition-run Syrian Civil Defense, first responders also known as the White Helmets, said the blast occurred in the village of Sarmada near the Turkish border, killing 36 people and wounding many others. The explosion collapsed two five-story buildings, burying many of the victims, it said.
The Britain-based Syrian Observatory for Human Rights put the death toll at 39, including 21 women and children.
An opposition media collective known as the Smart news agency, said the dead included civilians as well as members of the al-Qaida-linked Levant Liberation Committee.
The Observatory said an arms depot in the basement of a building had detonated. It said the depot was run by an arms dealer close to the Levant Liberation Committee.
Meanwhile, Syrian government forces fighting rebels in Idlib province have sent more reinforcements ahead of a potential offensive on the last major rebel stronghold in Syria.
The pro-government Al-Watan daily said Sunday that huge military reinforcements have reached the outskirts of Idlib province as a preliminary step to launch a wide-scale offensive.
Quoting military sources, the paper said that troops have reached the northern countryside of the neighboring Hama province as part of military preparations to recapture Idlib province.
The expected offensive on Idlib comes after government forces captured major rebel strongholds earlier this year near the capital Damascus and in the southern provinces of Daraa and Quneitra.
The paper said that the battle would be "comprehensive" starting from Hama's northern countryside to the southern countryside of Aleppo, adding that the target of the battle is to seize Idlib City.
Government airstrikes on the province on Friday killed dozens.
Pro-government activists said on social media that the elite Tiger Force, led by Brig. Gen. Suheil al-Hassan, arrived in northern Syria to spearhead what they called the "Dawn of Idlib" operation.