A passenger aboard an Air Canada flight from Toronto to Dubai opened a cabin door and fell to the tarmac before takeoff Monday evening, injuring themselves and causing lengthy delays.

The plane, a Boeing 777, was sitting on the tarmac at Toronto Pearson International Airport preparing for takeoff when the incident took place.

Air Canada confirmed to Global News that during the boarding of flight AC056, a passenger “who had boarded the aircraft normally,” opened a cabin door on the opposite side of the aircraft, instead of going to their seat while the aircraft was at the gate.

As a result, the passenger sustained injuries falling to the tarmac, and emergency services and authorities were called in.