Thirteen passengers were rushed to hospital after their Auckland-bound flight experienced serious turbulence, first responders told AFP on Monday.

"Our ambulance crews assessed and treated approximately 50 patients, with one patient in a serious condition and the remainder in a moderate to minor condition," Gerard Campbell of St John Ambulance New Zealand said, adding that 13 patients had been taken to hospital by ambulance.

Passengers reported chaos on board the Latam Airlines flight as it lost height suddenly. Passengers who were not wearing seatbelts were thrown up against the ceiling of the plane, and then injured themselves again when they fell and hit the seats. 

The flight was two hours into a three-hour flight from Sydney.