Early Friday, United Airlines flight 613 had to turn back to Lagos, Nigeria, after encountering an “unexpected movement,” leading to four passengers and two crew members being hospitalized for evaluation.

According to United’s statement to YSL News, “Our flight from Lagos to Washington D.C. returned due to a technical issue combined with an unanticipated aircraft movement. It landed safely in Lagos, and four passengers along with two flight attendants were taken to a hospital for minor injuries and have since been released. We are cooperating with aviation officials in both the U.S. and Nigeria to determine the cause.”

Images shared on social media depict food and drinks scattered throughout the plane’s cabin.

The aircraft, a Boeing 787, was carrying 245 passengers along with eight crew members and three pilots.

As the investigation unfolds, this incident echoes a similar one from March, where another 787 flying from Sydney to Auckland experienced “a technical event that resulted in a severe movement,” injuring 50 individuals.

Initial reports indicate that the March incident was partially triggered when a flight attendant inadvertently activated a switch that moved one of the pilot’s seats forward.

Zach Wichter is a travel reporter writing the Cruising Altitude column based in New York.