Alaska Airlines flight diverted after 'credible security threat'

An Alaska Airlines flight was diverted late Sunday after a "credible security threat related to an authorized occupant in the flight deck jump seat," the airline confirmed to ABC News.

The plane was scheduled to fly from Everett, Washington, to San Francisco before it diverted to Portland "following appropriate [Federal Aviation Administration] procedures and guidance from air traffic control," the airline said.

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

The suspect, Joseph David Emerson, was taken into custody, the Port of Portland confirmed.

The event is being investigated by law enforcement, the airline said.

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

This is a developing story. Please check back for updates.