Federal authorities are looking into severe turbulence that triggered “pandemonium” aboard a United Airlines flight into Billings, Mont., and sent five people to hospitals.

Passenger Ejay Old Bull of Billings says drinks had just been served and passengers were moving around the cabin when flight 1676 began to lurch violently about 55 minutes after it left Denver.

Old Bull says he watched the unrestrained woman next to him crash into the luggage bin overhead and briefly lose consciousness, while a crew member got bounced around in the galley just behind his seat.

United Airlines spokeswoman Christen David says three crew members and two passengers were taken to hospitals. One crew member remained hospitalized Tuesday.

David says the Boeing 737-300 involved has been taken out of service.

National Transportation Safety Board spokesman Terry Williams says authorities are investigating.

(AP)