An French rail official said on Saturday that a faulty rail joint may have caused the train derailment outside Paris that left six people dead and dozens injured.
Pierre Izard, an official with the national SNCF rail company, told reporters that investigators found that the joint had moved from its normal position.
Officials said that another train had traveled through the station just before the accident without incident. An investigation will determine why the rail joint, which is part of the switching system that moves trains from one track to another, detached.
Earlier, France's transport minister Frederic Cuvillier said that human error did not cause a train derailment.
The train was carrying 500 passengers, of whom 350 were in the four carriages that derailed. In all, nearly 200 people sustained injuries in the initial accident, when four train cars slid toward the station, some falling over.
The Friday night crash was France's deadliest in years, but Mr Cuvillier said it could have been worse and praised the driver who sent out an alert quickly, preventing a pile up.
Mr Cuvillier said it was unclear what did cause the accident, but authorities are looking into an error in the switching system as well as other possibilities.
Rescue workers said that dozens of people had been trapped, electrocuted or crushed when the Paris Austerlitz to Limoges “Teoz” express crashed at high speed in the suburban station of Brétigny-sur-Orge.
The accident happened at 5.15pm Paris time, about 30 minutes after the train left the Gare d’Austerlitz. The last four carriages of the seven-carriage train split from the rest and derailed, coming to rest at crazy angles across the tracks and station platforms. The first images from the scene showed passengers being dragged to safety through the roofs of carriages lying on their sides.
The express train was reported to have arrived at great speed on the southbound line into a suburban platform, rather than on its usual mainline track. Emergency workers said that along with the dead, nine others were critically injured and 60 less seriously hurt. But a spokesman stressed that the figures were only provisional. Some of the dead and injured were said to have been electrocuted by contact with the 25,000-volt overhead power lines which were brought down. The president of the French state railways (SNCF) Guillaume Pepy spoke last night of a “rail catastrophe”.
A spokesman said it was unclear whether the train had split before derailing or whether a fault in the track had caused the last carriages to break from the locomotive. Le Parisien reported that since May there had been problems with the points south of the station, which restricted the number of lines in use. All services into and out of the Gare d’Austerlitz have been suspended.
Additional reporting by Independent staff