PORTLAND, Ore. — A flight operated by Compass Air from Seattle to Los Angeles was diverted to Portland International Airport on Wednesday night after reports of a disruptive passenger.

The plane landed at 7:51 p.m. when Port of Portland police officers and the FBI responded. The suspect was identified Thursday as 21-year-old Douglas Smyser.

Witnesses and crew reported several incidents involving Smyser, the FBI said. Smyser threw his backpack in the aisle and claimed it wasn't his, refused to stay in his seat, paced the aisle and made several attempts to move toward the front of the plane, according the FBI. A crew member said Smyser told her "someone has a gun in the back row of this plane," the FBI said. 

The captain said the crew became concerned Smyser would rush the cockpit, so he decided to divert the flight and land in Portland, the FBI said.

As the plane approached for landing, a passenger used his body weight to physically block Smyser from leaving his seat until officers took him into custody, according to the FBI.

According to court documents, Smyser told police he's homeless in the Seattle area, and uses and heroin regularly.

Smyser faces a federal charge of interfering with a flight crew. He faces two state charges including menacing and disorderly conduct.

He is expected to make a court appearance in Portland on Friday.