Strasbourg - Dozens of people were injured in a collision between two streetcars in Strasbourg on Saturday.

However, according to the authorities, none of the injured were in mortal danger.

The two streetcars collided with great force in a tunnel at the train station in the Alsatian metropolis. The cause of the accident was initially unclear.

It was a "brutal collision" between the streetcars on a track below the station, said Strasbourg Mayor Jeanne Barseghian, who rushed to the station after the accident .

There were differing reports on the number of casualties. The prefecture announced that preliminary estimates put the number of injured at 30 to 35. The fire department put the number of injured at around 50.

Previously, initial information from the prefecture had stated that at least 20 people were injured.

The emergency services cordoned off the entrance to the station and ambulances were parked in the exclusion zone. Some of the injured were carried into the ambulances, others were treated inside the station.

The video from an eyewitness showed the two streetcars badly damaged in the tunnel. One of the streetcars appeared to have derailed.

The public prosecutor's office launched an investigation into the cause of the accident, according to the prefecture.

Patrick Maciejewski, President of the Strasbourg transport company CTS, said that several demonstrations had caused traffic disruptions in the city in the afternoon and that some streetcars had had to be reorganized as a result.

According to Maciejewski, one of the two streetcars had braked before the collision and started to move backwards.

An eyewitness named Johan, who did not want to give his surname, told the AFP news agency that the streetcar had reversed at full speed. "There was a problem with the brakes," this witness reported. "We heard a strong impact, a big bang."