A terrifying video shows a fast-moving NJ Transit train rolling along an overpass in Linden with one of its doors wide open — and railroad officials are investigating.

A Twitter user with the handle GIO shot the video on a Northeast Corridor train during the Tuesday morning rush hour, he told The Post.

The train goes over at least one big overpass with a busy street below while flying along with nothing to keep commuters from falling out. The six-second shot also pans to scared riders hugging the far wall of the train to get as far away from the open door as possible.

NJTransit officials said they are aware of the incident and are investigating.

“As soon as the train crew became aware of the situation, the door was immediately closed and locked and the train was taken out of service when it arrived at its final destination of Penn Station New York,” said agency spokesman Jim Smith.

“The train was then taken to the shop for a full inspection.”