AMARILLO, Texas (AP) — The captain of a JetBlue aircraft yelled about a bomb and had to be locked out of the cockpit and restrained Tuesday as the Las Vegas-bound flight was diverted to Texas, passengers said.JetBlue Airways said in a statement that the captain of Flight 191 from New York had a “medical situation” and that the pilot in command of the aircraft elected to land in Amarillo about 10 a.m.Grant Heppes, a 22-year-old passenger from New York City, told The Associated Press that a man in a JetBlue uniform walked from the cockpit to the back of the plane, but that he started to become disruptive when he was barred from getting back inside.”Once he got back to the front of the plane I heard him scream, ‘Let me in!’” Heppes said.Heidi Karg, a passenger on the flight, told CNN that the man was shouting “I need the code, gimme the code, I need to get in there.” The pilot used the announcement system to call for someone to restrain him and some male passengers wrestled him to the ground, she said.Karg said she thought the man was the captain of the flight but that she wasn’t certain.”We heard the word ‘bomb,’” Karg said. “We didn’t know exactly what was going on.”Most of the passengers were “shocked and confused,” Heppes said by phone from the airport at Amarillo.”Nobody was very loud except for the people trying to help out. Everybody was just standing up and not really sure what was going on. It was very hard to tell,” he said.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, Heppes said.The FBI was coordinating an investigation with the airport police, Amarillo police, the Federal Aviation Administration and the Transportation Safety Administration, according to agency spokeswoman Lydia Maese in Dallas.She declined to comment on whether any arrest had been made.___Associated Press writers Oskar Garcia in Las Vegas and Betsy Blaney in Lubbock, Texas, contributed to this report.