Two trains collided on Wednesday in northeastern France close to the border with Luxembourg, killing at least four people.
It is feared the number of dead may rise.
The late morning crash in Zoufftgen, about 2 kilometres (1.2 miles) south of the border with Luxembourg, involved a passenger train and a freight train that collided head-on, a spokesman for French rail operator SNCF said.
Rail officials said the train drivers - one French, another from Luxembourg - as well as a person on the tracks also were believed dead.
The SNCF had said about 10 people on the passenger train were believed to have been killed and 20 others injured.
However, the local government for the Lorraine region, later revised its casualty figure downward from 10 to four dead, and said nine others were trapped inside the wreckage.
Several cars of the freight train were either crumpled up, bent skyward or tipped over on their sides.
The passenger train had been travelling from Luxembourg to the French city of Nancy.
The train line it was travelling on was being repaired, so it switched onto a second track, hitting the oncoming freight train, it was reported.
More than 100 rescue workers were at or heading to the crash site to set up a mobile hospital and treat victims, a local fire chief said.