STRASBOURG, France: Four children escaped serious injury when a high-speed train derailed during a test run at the weekend in northeastern France, killing 11, prosecutors said Monday.

The dead were among 53 aboard the doomed train of whom 42 were injured including the children aged between 10 and 15, local deputy prosecutor Alexandre Chevrier told a press briefing.

“This toll is unfortunately not final, since there are four people whose lives are still in danger,” Chevrier said. “Luckily (the children) were only slightly injured.”

The investigation will determine why guests were allowed on board for the test run, he added.

The spectacular accident Saturday saw the next-generation TGV (train a grande vitesse, or high-speed train) strike a bridge before jumping the track and breaking in two, landing partially in a canal in the town of Eckwersheim, some 20 kilometers (12 miles) north of Strasbourg.

It was the first fatal accident for France’s flagship train service since it went into service in 1981.

Officially, 49 technicians and railwaymen were assigned to test the new TGV, which was due to go into service next spring.

Chevrier described the driver of the train, who suffered only minor injuries, as “very experienced” and said he had told investigators that he had kept strictly to the designated speed for the part of the track he was on — 176 kilometers per hour (109 mph). A source close to the inquiry said Saturday that the train was running at around twice that speed, 350 kph, when it derailed.

Investigators will be able to establish the exact speed by analyzing the train’s black box data storage units, which were recovered apparently intact, he said.

On Sunday, the head of SNCF Guillaume Pepy said the French railway company would assume full responsibility for “all the victims... whether it’s railwaymen or guests.”

Pepy said the company did not approve of having guests on test runs.

Sabotage or an attack have not been ruled out, he added, but were considered unlikely. While there have been derailments of French TGV trains in the past, Saturday’s was the first to claim lives.

The new trains are designed to speed up the journeys between Paris and eastern France, eventually extending to Luxembourg.

But it was now “reasonable to assume” that the high-speed Paris-Strasbourg line would not be opened next April as planned, SNCF board member Jacques Rapoport said.