Turbulence on an Air Canada flight from China injured multiple passengers on Wednesday, forcing it to land in Calgary, Alberta, the airline said.

Twenty-one passengers were transferred to hospitals from the airport - eight with non-life-threatening injuries and 13 sent for observation, it said in a statement.

Air Canada flight 88 departed from Shanghai and was headed to Toronto, carrying 332 passengers and 19 crew.

The airline said it would be making arrangements to accommodate the other passengers, including those continuing on to Toronto, and that the incident was being investigated.

There was no immediate indication of what caused the turbulence.