Off-duty pilot charged with 83 counts of attempted murder for allegedly trying to shut off engines on Alaska Airlines flight

An off-duty pilot is charged with 83 counts of attempted murder after he allegedly tried to shut off the engines by pulling the fire extinguisher handles on an Alaska Airlines flight, according to officials.

The plane was scheduled to fly from Everett, Washington, to San Francisco before it diverted late Sunday to Portland after a "credible security threat related to an authorized occupant in the flight deck jump seat," the airline confirmed to ABC News.

The suspect allegedly tried to pull the fire extinguisher handles on the engines, preliminary information obtained by investigators indicated, according to a federal official briefed on the probe. The suspect was overwhelmed by flight crew and subdued and then handcuffed to a seat, the federal official told ABC News.

The suspect, Joseph David Emerson, was taken into custody, the Port of Portland confirmed. Emerson is charged with 83 counts of attempted murder, according to the Multnomah County Sheriff's Office. He is also facing 83 counts of reckless endangerment, a misdemeanor, and one felony count of endangering an aircraft.

The suspect was en route to San Francisco, where he was scheduled to be on a flight crew of a 737, the official said.

Alaska Airlines said the off-duty pilot was sitting in the flight deck jump seat -- which is in the cockpit -- and "unsuccessfully attempted to disrupt the operation of the engines."

He was heard in the moments prior saying something similar to, “I’m not right,” a federal official told ABC News.

The captain and first officer "quickly responded," Alaska said, adding engine power was not lost and the crew secured the aircraft without incident.

There were 80 passengers and four crew members on the flight, according to Alaska.

Passenger Aubrey Gavello told ABC News, "We didn't know anything was happening until the flight attendant got on the loudspeaker and made an announcement that there was an emergency situation and the plane needed to land immediately. … About 15 minutes later, she got back on and said that there was a medical emergency."

Passenger Alex Wood said the pilot announced that "there was a disturbance in the cockpit."

Gavello said she heard a flight attendant tell the suspect, "We're going to be fine, it's OK, we'll get you off the plane."

"So I really thought it was a serious medical emergency," she said.

Wood added, "It was very professional, handled very calmly, and we didn't really know what was going on until we landed."

Once the plane landed, Wood said police went to the back of the plane and escorted a handcuffed man off the plane. He noted that the suspect "was wearing a lanyard, a sweater. Looked like an airline employee."

Gavello said, "After we did land and the gentleman was escorted off, the flight attendant got back on the speaker and said, plain and simple, 'He had a mental breakdown. We needed to get him off the plane immediately.'"

The Federal Aviation Administration said in a statement to carriers that the incident is "not connected in any way shape or form to current world events."

The event is being investigated by law enforcement, the airline said. The FBI confirmed it is looking into the incident and "can assure the traveling public there is no continuing threat related to this incident."

Secretary of Transportation Pete Buttigieg said in a statement, "I am grateful for the professional flight crew and air traffic controllers who stepped up to guide this plane safely to Portland. FAA supports law enforcement in their response and will be focused on any safety considerations for the future that emerge from investigations."

The pilots union Air Line Pilots Association, International in a statement praised the pilots and crew who safely landed the plane and said it's fully cooperating with authorities.

The union added, "The airline pilot profession in North America is one of the most highly vetted and scrutinized careers, and for good reason. For decades, the United States has pioneered a proactive approach to improving aviation safety and maintaining a healthy work environment for pilots. In addition, U.S. pilots are continuously evaluated throughout their careers through training, medical exams, crew resource management, and programs such as the Line Operations Safety Audit, as well as by the airline and during random flight checks by the Federal Aviation Administration."