PARIS (AFP) – Rail investigators said Saturday they had found a fault in the track where a train derailed near Paris, killing six people and injuring dozens more.
Friday's derailment may have been caused by a connecting bar that had come loose at a rail switchpoint at Bretigny-sur-Orge station, about 25 kilometres (15 miles) south of Paris, said rail operator SNCF.
The joint bar "broke away, it became detached and came out of its housing", said Pierre Izard, the SNCF's general manager for infrastructure.
It "lodged itself at the centre of the switch, prevented the normal progression of the train's wheels and seems to have caused the train's derailment," he said.
The switch had been checked on July 4 and another train had passed over it half an hour before the accident, said the company.
The SNCF has ordered immediate checks of some 5,000 similar joints on its network.
Transport Minister Frederic Cuvillier said human error was not to blame for the accident.
He praised the train's driver who he said "had absolutely extraordinary reflexes by sending the alert immediately", preventing a collision with an oncoming train.
But France's regional rail lines were out of date after the SNCF focused much of its attention in recent years on high-speed TGV lines, he said.
"We cannot be satisfied with rolling stock that is 30 years old," Cuvillier added. "The situation is severe, with the deterioration in recent years of traditional lines because of a lack of resources."
A railway passenger association also denounced what it called "rust-bucket trains" and the practice of coupling different types of trains together. It called for proper inspections.
President Francois Hollande was likely to face tough questions about the accident on Sunday, when he gives an interview to leading French television channels to mark the Bastille Day holiday.
A minute of silence was held at noon (1000 GMT) Saturday on all French trains and in all stations for the victims of the accident, which took place as many were leaving for summer holidays.
The local prefect's office said the dead were four men and two women, aged between 19 and 82.
A source close to the investigation told AFP the dead included a couple in their 80s from Bretigny, three men aged 19, 23, and 60, and a young woman whose exact age was not immediately clear.
"Two were probably on the train while four were on the platform" hit by the train, said the source.
The train came off the tracks and crashed into the station platform at 5:14 pm Friday, as it travelled at 137 kilometres (85 miles) per hour on its way from Paris to the west-central city of Limoges.
Four carriages of the train jumped the tracks, three of which overturned. One carriage smashed across a platform and came to rest on a parallel track; another lay half-way across the platform. There were 385 passengers on the train.
The local prefect said that death toll of six was final after the first of the four damaged carriages was removed from the tracks. They had feared finding more bodies in the wreckage.
Michel Fuzeau, the prefect of the Essonne region, said that 16 victims of the crash were still in hospital and the condition of those most seriously injured had stabilised.
Health officials have said at least 50 people had been treated for injuries.
The SNCF, judicial authorities and France's BEA safety agency have each launched separate investigations into the accident.
Witnesses said the crash site resembled a war zone, with 57-year-old passenger Marc Cheutin saying he had to "step over a decapitated person" to exit the carriage he had been travelling in.
The accident was still disrupting Paris commuter lines on Saturday. Paris-Austerlitz station, where the train had departed from on Friday, was expected to remain closed for several days.
Officials meanwhile dismissed reports from police unions that a group of people pretending to be part of rescue efforts had attempted to steal from the victims, and that gangs had thrown stones at emergency workers.
The Red Cross and France's SAMU emergency medical service denied having faced any problems in carrying out their work.
Hollande, who visited the crash site soon after the accident, stressed that ordinary people had gone to help the crash victims.
The derailment was France's worst rail accident since 2008, when a train collided with a schoolbus, killing seven schoolchildren.