Dozens of people were injured after a flight from Australia to New Zealand experienced a “technical event” that produced a sudden movement, according to the flight’s operator, with witnesses telling local media that passengers were suddenly thrown around the cabin.

Approximately 50 people were treated for injuries on arrival in Auckland, including one person in serious condition, emergency medical service provider Hato Hone St John Ambulance told CNN. It said 12 patients had been sent to hospital.

Affected passengers and cabin crew “received immediate assistance and were evaluated or treated by medical staff at the airport as needed,” according to a statement to CNN by LATAM Airlines.

“Flight LA800, operating the Sydney — Auckland route today, had a technical event during the flight which caused a strong movement,” the statement said, which added the plane landed as scheduled in Auckland on Monday.

The statement did not elaborate on what the technical event was.

Aviation officials in Chile say investigators in New Zealand will probe the “technical event” on a Chilean Boeing 787 that injured 50 passengers.

“We regret the situation experienced by passengers, while we reiterate our commitment to the safety of air operations,” said a statement from Chile’s Directorate General of Civil Aeronautics.

Chile’s aviation agency is also appointing an “accredited representative” in New Zealand to “participate in the investigation.”

New Zealand’s equivalent to the National Transportation Safety Board is “aware of the reported incident,” Transport Accident Investigation Commission spokesperson Simon Pleasants previously told CNN. “We are gathering further information to inform a decision as to whether to open an inquiry.”

CNN has reached back out to authorities in New Zealand to confirm they will be investigating the incident.

Meanwhile, Boeing has confirmed that the incident happened on board one of its planes, adding that it is working to gather more information.

The plane was a Boeing 787-9 Dreamliner, according to flight tracking website FlightAware.

“We are working to gather more information about the flight and will provide any support needed by our customer,” a Boeing spokesperson said in a statement to CNN.

LATAM Airlines is Chile’s flagship carrier and stops regularly in Auckland en route to Santiago.

St John Ambulance added that 14 units, including seven ambulances, responded to an incident at Auckland International Airport involving an in-bound aircraft.

A passenger on board the flight called Jacinto, who spoke with CNN affiliate RNZ, said there was a “mid-air drop.”

“People flew through the cabin,” he said. “People got pretty injured.”

Multiple passengers were not wearing their seatbelts at the time of the sudden drop, he added.

“People were really scared as well.”

Another passenger, which RNZ named as Valentina, said that the plane “just stopped,” and that “people were flying around.”

“Blood was on the ceiling, people [flew] and broke the ceiling of the plane,” she said, adding that she was “very scared” to get on a plane again.

Valentina suffered minor injuries but was treated by medical crew once the plane landed.