(AP) - A JetBlue captain who screamed that Iraq or Afghanistan had planted a bomb on a Las Vegas-bound flight was locked out of the cockpit, tackled and restrained by passengers Tuesday, passengers said.

The captain of Flight 191 from New York JFK International Airport had a "medical situation" and that the pilot, who subsequently took command of the aircraft, elected to land in Amarillo, Texas about 10 a.m., JetBlue Airways said in a statement.

Josh Redick, a passenger sitting near the middle of the plane, said the pilot "stormed out" of the cockpit.

Tony Antolino, a 40-year-old executive for a security firm, said the captain walked to the back of the plane, that he seemed disoriented and agitated, then began yelling about an unspecified threat linked to Iran, Iraq and Afghanistan.

"They're going to take us down, they're taking us down, they're going to take us down. Say the Lord's prayer, say the Lord's prayer," the captain screamed, according to Antolino.

"He was irate," Redick said. "He was spouting off about Afghanistan and souls and al-Qaida."

Gabriel Schonzeit, who was sitting in the third row, said the captain said there could be a bomb on board the flight.

"He started screaming about al-Qaida and possibly a bomb on the plane and Iraq and Iran and about how we were all going down," Schonzeit told the Amarillo Globe-News.

The captain had been exhibiting "erratic behavior," so the pilot locked him out of the cockpit, the Federal Aviation Administration said in a statement.

Antolino, who said he sat in the 10th row, said he and three others tackled the captain as he ran for the cockpit door, pinned him and held him down while the plane landed at Rick Husband Amarillo International Airport.

"That's how we landed," he said. "There were four of us on top of him. ... Everybody else kind of took a seat and that's how we landed."

An off-duty captain who just happened to be a passenger on the flight went to the flight deck and took over the duties of the ill captain "once on the ground," the airline said in a statement. It didn't elaborate.

Shane Helton, 39, of Quinlan, Okla., said he saw emergency and security personnel coming on and off the plane as it sat on the tarmac at Rick Husband Amarillo International Airport.

"They pulled one guy out on a stretcher and put him in an ambulance," said Helton, who went to the airport with his fiancée to see one of her sons off as he joined the Navy.

Helton said the ambulance then sat on the tarmac next to the plane for more than 30 minutes.

JetBlue said the ill captain was taken to a medical facility in Amarillo.

Once on the ground and off the plane, authorities interviewed each of the passengers, according to 22-year-old passenger Grant Heppes, of New York City.

The FBI was coordinating an investigation with the airport police, Amarillo police, the FAA and the Transportation Safety Administration, according to agency spokeswoman Lydia Maese in Dallas.

She declined to comment on whether any arrests have been made.

As a result of the incident, the FAA will review the captain's medical certificate - essentially a good housekeeping seal of approval that the pilot is healthy. All pilots working for scheduled airlines must have a first class medical certificate. The certificates are required to be renewed every year if the pilot is under 40, every six months if 40 or over.

Passenger video taken aboard plane: