The regional TER train crashed at Lunel, which is between Nimes and Montpellier in the south of France (see map below).
At least one helicopter was at the scene to carry the injured to a nearby hospital while others gathered on the train tracks.
An image shared by the local branch of France Bleu showed a large tree that appeared to have completely covered the tracks.
Meanwhile, tweets from passengers (below) showed the damage from the collision, including what appears to be a hole in the wall of the train and glass from broken windows all over the floor.
Trains in both directions in the area faced severe delays following the accident.
The crash occurred near Lunel, north of Montpellier in southern France. Photo: Google Maps