Extreme turbulence is being blamed for a terrifying incident that injured 25 passengers on an Air Canada flight AC88 from Shanghai to Toronto over the Christmas holidays, forcing the plane to make an unscheduled stop in Calgary.

Twenty-one passengers were taken to hospital including three children. Six of the injured are described as being in serious condition. None of the injuries are said to be life-threatening. The injured were seen being taken out of the airport in stretchers and gurneys, with some wearing neck braces. Seven passengers are said to have possible neck or back injuries.

AC88 was traveling with 332 passengers and 19 crew members when the turbulence hit the Boeing 777.

Passengers on board the flight described a chaotic scene in which passengers were thrown out of their seats as oxygen masks descended from the ceiling. Passenger Connie Gelber called the ordeal a “flight from hell”.

“It was frightening,” said Gelber. “Honestly we didn’t know if we were going to live or die.”

Gelber said the turbulence was unlike anything she had ever seen before. “Like you see in the movies, where they all go up to the ceiling, everything went up to the ceiling that wasn’t anchored,” she said, adding that she saw a girl get thrown out of her seat.

Another passenger named Liu Pinzhou confirmed that the turbulence on board the plane was severe, saying that people “just flew.” “It was crazy,” Liu said.

Passenger Bing Feng said lots of screaming could be heard once the turbulence hit. “I heard lots of people screaming, like what you would hear on a roller coaster,” said Bing. “When you are in the situation, of course (you fear the worst). You saw all the oxygen masks drop.”

In the absence of a medical doctor, a Toronto-based periodontist named Dr. Suzanne Caudry helped assess the injured passengers for head and neck injuries.

“Their heads had literally hit the ceiling and actually gone through the plastic … The fact that nobody was seriously injured is a miracle,” said Caudry.

Air Canada and the Transportation Safety Board of Canada have said a full investigation into the incident will be performed. Here’s a video taken by a passenger of the turbulence: