At least 10 people were killed and five more were missing after a French high-speed train derailed during a test run, the first fatal accident since the TGV trains were introduced more than 30 years ago.
The victims were among the team of 49 technicians aboard the train which derailed on Saturday near Strasbourg, northeastern France. There were no other passengers.
The train was running at around 350km/h on a high-speed line as part of testing for the next generation of TGV due to go into service in early 2016, a source close to the inquiry said.
Another 37 people were injured, including 12 people in critical condition, local officials said.
Five others were said to be missing with some people "still trapped under the carriages", according to French Environment and Sustainable Development Minister Segolene Royal.
The train ended up under a bridge in the water of a roughly 40-metre wide canal.
Search and rescue teams, with sniffer dogs, were set to continue working throughout the night.
Royal, who visited the crash site later on Saturday, as did transport secretary Alain Vidal, called it "an apocalyptic scene" and expressed her solidarity with the family of the victims.
The accident happened "because of excessive speed" at Eckwersheim in eastern France as technicians were on board for testing, said Dominique-Nicolas Jane, a senior official in the Alsace region.
However, police said the cause of the crash had not been determined. A source close to the investigation said dozens of technicians were aboard.
The accident is the first fatal accident since the TGV high-speed train went into service in France in 1981.
The damaged silver and black front on the train could be seen lying in the canal under a bridge, with the next carriage straddling the bank and the water.
A great plume of black smoke could be seen from several kilometres away, including from the suburbs of Strasbourg near the German border.
Youngsters playing at a nearby skate-park spoke of acrid fumes.
A police dive team, helicopters and tens of rescue vehicles were sent to the scene in response to the crash.
The accident occurred in a non-residential area, though with some house-boats elsewhere along the canal.
A search was under way to retrieve the train's black box data storage units, said Stephane Ottavi, police commander for the surrounding Alsace region.
Saturday's accident happened with France on high alert following a string of deadly attacks in Paris late on Friday.
However, there were no signs that the train derailment was anything other than an accident during testing.