Several workers were injured when the nose gear on a Boeing 787-9 Dreamliner collapsed while the plane was parked at Frankfurt Airport in Germany on June 4. The workers were on board the plane, operated by Lufthansa, when the incident occurred.

According to The New York Times, the airline said the plane’s nose gear “unexpectedly retracted” at 12:45 p.m. local time, just over an hour before the plane was scheduled to depart for a nearly 12-hour flight to Los Angeles, with 165 passengers.

Video of the incident posted on social media shows the nose of the plane crashing to the ground while it was attached to a jet bridge at a gate.

Passengers had not yet boarded, but two Lufthansa cabin crew members and an unspecified number of service workers who were on board sustained minor injuries and were taken to a hospital for treatment, the airline said.

Lufthansa said the cause of the accident was under investigation and that experts were examining the plane before moving it to a hangar for further inspection. The 787-9 Dreamliner, a twin-engine, long-haul jet that can seat more than 290 passengers, can weigh as much as 556,998 pounds, or 279 tons, at takeoff, Lufthansa says.

The flight to Los Angeles was canceled.

Boeing said in a statement that it was aware of the incident, and is supporting its customer, Lufthansa.