A flight to Washington, D.C., returned to Nigeria after “unexpected aircraft movement” caused injuries, United Airlines said. A statement from United emailed to The Hill on Monday said that one of its flights headed for Washington,

United Airlines said it was cooperating with U.S. and Nigerian investigators to determine what exactly happened on the flight.

United Airlines flight from Nigeria to Washington, D.C., was forced to return to Lagos after experiencing a technical issue and unexpected aircraft movement.