A video has been released showing two masked men blocking the door of a suburban train in Hamburg with a professionally built wall. The stunt, which took place in late April, caused quite a stir as the train made its way through Hamburg for hours before being noticed by train staff.

Commuters filmed and took pictures as the doors of the train opened only to reveal a concrete wall behind it. Since then police are investigating the incident which caused several 1,000 euros' worth of damage, according to a train line official, because the train had to be out of order for more than 12 hours following the discovery of the wall.

The just-released video shows two masked men wearing Deutsche Bahn warning vests mixing cement and carrying building materials to the parked train carriage where they begin to build the wall in broad daylight. The men have enough time to carefully measure the width of the door, cut the large white blocks to size and cement them into place before the train sets off. The video then shows the confused reactions of passengers as they find their way into the carriage blocked by the wall.

The video called Moses & Taps – The Wall was released on 13 July by Nofugazi, a fashion label associated with the graffiti scene, but the site was quick to point out it does not know who was behind the video.

Graffiti artists Moses & Taps are well known on the scene and police are said to be investigating their identity.