Thirty people were injured, one critically, after a United Airlines jet heading for Los Angeles hit heavy turbulence and was diverted to Denver early today.
The flight originated at Dulles International Airport near Washington DC, the Federal Aviation Administration said.
It landed safely at Denver International Airport, Colorado, at around 7.45pm local time (2.45am BST), and was met by medical crews.
FAA spokesman Ian Gregor said 26 passengers and four crew members were injured. One person was critically injured.
Denver Health Medical Centre spokeswoman Dee Martinez said 21 people had been transported to five hospitals. Most of them had moderate injuries to the head, neck or back.
United Airlines spokeswoman Megan McCarthy said Flight 967 was carrying 255 passengers and 10 crew members.
She said the crew decided to play it safe and land in Denver to tend to the injured.
The turbulence was "just a huge up and down", said passenger Kaoma Bechaz, a 19-year-old Australian in the US to visit her boyfriend.
She told the Denver Post that the head of the woman sitting next to her hit the side of the cabin, leaving a crack above the window, and a girl across the aisle flew into the air and hit the ceiling.
Ms Bechaz said she was not thrown around because her seat belt was tight.
It is not the first time this year that United Airlines has encountered heavy turbulence.
In February about 20 people were injured when a United flight experienced turbulence halfway through a 13-hour trip from Washington DC to Tokyo. The Boeing 747 had 263 people on board.
In May, 10 people suffered injuries, including broken bones, on a United flight that hit severe turbulence over the Atlantic Ocean on its way from London to Los Angeles. The Boeing 777 was diverted to Montreal, Canada.