JetBlue domestic flight 191 from New York to Las Vegas has made an emergency landing amid a medical scare over the captain, the airline has said.

JetBlue 191 was carrying 135 passengers when it landed in Amarillo, Texas, about three-and-a-half hours into the flight.

One passenger said a man thought to be the flight captain began shouting, possibly about a bomb, and had to be restrained.

Local police and the FBI are said to be investigating the incident.

“We heard the word <<bomb>>,” passenger Heidi Karg told CNN.

“We didn’t know exactly what was going on.”

Heidi Karg said she heard the captain shout: “I need the code, gimme the code, I need to get in there.”

JetBlue domestic flight 191 from New York to Las Vegas has made an emergency landing amid a medical scare over the captain

Another passenger, Grant Heppes, told the Associated Press that he saw the man walk from the cockpit to the back of the plane. He was barred from going back in and then became disruptive.

Grant Heppes said many passengers were “shocked and confused”.

“Nobody was very loud except for the people trying to help out. Everybody just standing up and not really sure what was going on. It was very hard to tell,” he said.

JetBlue has said the pilot in charge of the plane decided to land at about 10:00 a.m local time.

Once on the ground in Amarillo the crew member was taken to a local medical facility and an off-duty captain who was on the flight by chance took over the role, JetBlue said.

According to Grant Heppes, the ambulance was parked beside the plane for about half an hour.

One man at the airport, Shane Helton, told the Associated Press that emergency personnel were on the tarmac.

“They pulled one guy out on a stretcher and put him in an ambulance,” he said.