According to ABC News, the captain of Flight 191, identified as Clayton Frederick Osbon, went to the bathroom and came out behaving erratically, foaming at the mouth and ranting about a bomb on board.
The co-pilot locked Osbon out of the cockpit. That apparently angered Osbon, and he began pounding on the door demanding to be let in.
Fearing for their safety, as many as five passengers tackled and pinned the captain. One of those passengers, former New York City Department of Corrections Officer David Gonzalez, put Osbon in a chokehold until the unruly pilot passed out, ABC News reported.
"He started to curse at me and started to tell me, 'Hey, you better pray, Iraq and Iran,'" Gonzalez said. "So I said, 'You know what? I'm going to show you what Iraq and Iran is,' and I took him in a chokehold."
An off-duty JetBlue pilot who happened to be on board helped land the plane safely in Amarillo about 10 a.m.
JetBlue said on its website that the plane landed due to "a medical situation involving the captain," and noted that all the passengers on board were safe.
Osbon was led off the plane in a stretcher, restrained by medical personnel. Osbon leaned his head back and could be heard screaming. He was taken to a hospital for evaluation. Early indications are he had a panic attack.
Osbon's Twitter account describes him as a "JetBlue Flight Standards Captain-Airbus 320 Leadership Coach." According to his Facebook page, he's been a commercial pilot since 1979. He's been a pilot of JetBlue since 2000.
The FBI was coordinating an investigation with the airport police, Amarillo police, the FAA and the Transportation Safety Administration.
Passengers on Flight 191 made it to their destination in Las Vegas just after 4 p.m.