ECKWERSHEIM (France) • At least 10 people were killed and 37 injured after a French high-speed train derailed during a test run on Saturday, with "several children" on board, local officials said.

This was 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 near the city of Strasbourg in north-eastern France.

"There were several children on board," a spokesman for France's state rail company SNCF said.

He added however that he was unable to say if any of the children were among those who died in the derailment in Eckwersheim, near Strasbourg. No other details of the children were available.

The train was running at around 350kmh on a high-speed track as part of testing for the next generation of TGV trains due to go into service next year, a source said.

Another 37 people were injured, including 12 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 40m-wide canal.

Ms 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 families of the victims.

The accident happened "because of excessive speed" at Eckwersheim as technicians were on board for testing, said Alsace region senior official Dominique-Nicolas Jane.

However, police said the cause of the crash had not yet been determined.

The damaged silver and black front of 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 the smell of acrid fumes.

A police dive team, helicopters and tens of rescue vehicles were sent to the scene in response to the crash.

Search-and-rescue teams, with sniffer dogs, were set to continue work throughout the night.

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 police commander Stephane Ottavi of the surrounding Alsace region.

Saturday's crash was the first fatal accident since the TGV (which stands for high-speed train in French) went into service in France back in 1981.

While there have been derailments of French TGV trains in the past, none had this kind of tragic outcome.

Until now, the worst train accident in France in recent years occurred in July 2013 when a commuter train derailed in a Paris suburb, killing seven people and injuring dozens more.

Saturday's accident happened with France on high alert following a string of deadly terrorist attacks in Paris late on Friday.

However, there were no signs that the train derailment was anything other than an accident during testing.

AGENCE FRANCE- PRESSE