The nose gear on a Boeing 787-9 Dreamliner operated by Lufthansa collapsed while the plane was parked at Frankfurt Airport in Germany on Thursday. Several workers who were on the plane were injured, the airline said.

A twin-engine, long-haul jet that can seat more than 290 passengers, the 787-9 Dreamliner can weigh as much as 556,998 pounds, or 279 tons, at takeoff, Lufthansa says.

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. A worker in a yellow vest who was standing on the ground, near the nose, steps back quickly to avoid being hit.

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.

The airline said the cause of the accident was under investigation and that experts were examining the plane before they planned to move it to a hangar on Thursday evening for further inspection.

The flight to Los Angeles was canceled.

Boeing said in a statement: “We’re aware of the incident and are supporting our customer,” Lufthansa.

The first Dreamliner was delivered in 2011 to All Nippon Airways, Japan’s largest airline. There are more than 1,175 in use today, according to Boeing, which says the planes operate out of more than 520 airports and log 2,100 flights each day.