The U.S. National Transportation Safety Board said on Monday it is investigating a United Airlines flight on Friday from Lagos, Nigeria to Washington D.C., in which a sudden aircraft movement led to injuries of passengers and cabin crew.

In an update, Nigerian officials said an additional 27 passengers and 5 crew members suffered minor injuries in the incident. In all, 38 were hurt.

A United Airlines flight from Africa to Washington D.C. had to turn around on Thursday after a "technical issue" caused "unexpected aircraft movement," the airline said.

The US National Transportation Safety Board is investigating a United Airlines Holdings Inc. flight that turned back to Nigeria after a “sudden aircraft movement” occurred, injuring passengers and crew.

New video shows frightening moments onboard a United Airlines flight bound for Washington, D.C., after what officials are calling a “technical issue” occurred.

It is unclear what caused the jolt; United Airlines has said the cause was not severe turbulence, and that it is “working with aviation authorities in the US and Nigeria to understand the cause.”