Two trams collided in a tunnel in the eastern French city of Strasbourg on Saturday, injuring at least twenty people, the authorities said.
Strasbourg was the first major French city to re-introduce its tram service, in 1994. Since then, there have been no major accidents.
"Twenty people" have been injured, said a spokesman for the prefecture, citing a preliminary estimate. He added that the cause of the accident had not yet been established.
The trams collided near Strasbourg's rail station.
A large security perimeter has been set up in front of the station, where numerous ambulances have taken up position, according to an AFP journalist at the scene.
A video posted by a witness on social media shows a chaotic scene with the two trams significantly damaged in the tunnel near the station.
One of the trams appears to have derailed as a result of the impact.