A high-speed TGV train accident in eastern France at the weekend that left 11 people dead was the result of "late braking", rail company SNCF says.
The spectacular accident saw the next-generation train strike a bridge before jumping the track and breaking in two, landing partially in a canal.
The train, which was on a test run, began braking a kilometre too late as it approached a stretch of older track, SNCF said on Thursday.
There were seven people in the driver's wagon, instead of the authorised four.
The crash in the town of Eckwersheim, 20 kilometres north of Strasbourg, was the first fatal accident for France's flagship train service since it went into service in 1981.
The company said it would launch disciplinary proceedings against those responsible, and would investigate why there were children on board a test run.
There were a total of 53 passengers on the doomed train of whom 42 were injured including children aged between 10 and 15, prosecutors said earlier this week.
The head of the state-owned SNCF, Guillaume Pepy, said such an accident "obviously" would not have taken place during a passenger journey when automatic safety mechanisms would have been triggered.
Officially, 49 technicians and railwaymen were assigned to test the new TGV, which was due to go into service next spring.