An official says a faulty rail joint may have caused the derailment.
Pierre Izard, an official with the SNCF rail company, told reporters Saturday that investigators found the joint had moved from its normal position.
Some cars slid toward the station, crushing part of the metallic roof over the platform. Images from the scene on French television showed gnarled metal and shards on the platform, and debris from the crash clogging the stairwell leading beneath the platform.
“The train was unrecognizable. There was nothing, but metal scraps,” 20-year-old accounting apprentice Ben Khelifa said. His commuter train was on the adjacent track.
“The train just collapsed, just like that, on its side ... There was blood,” Khelifa said.
He added that he was one of a number of passengers in the adjacent train that went to help pull trapped survivors out of the wreckage.
“People were screaming, people were asking where their children were,” he said.
Another witness, Bazgua El Mehdi, 19, said, “I heard a loud noise. A cloud of sand covered everything, then the dust dissipated. I thought it was a freight train, but then we saw the first casualties ... Many passengers on the (train) were crying.”
It was unclear whether all the casualties were inside the train, or whether some had been on the platform, or how fast the train was traveling. The head of the SNCF rail authority, Guillaume Pepy, called it a “catastrophe.”
The cause of the crash was under investigation. The train's third and fourth cars initially derailed, which then knocked the other cars off the track, Pepy said.
The Interior Ministry said six people died in the crash and nine were in critical condition. Earlier, Interior Minister Manuel Valls said seven people had been killed.
The SNCF said the train was carrying about 385 passengers when it derailed Friday evening and crashed into the station at Bretigny-sur-Orge, about 12 miles south of Paris. The train was headed from Paris to Limoges, a 250-mile journey, and was about 20 minutes into what would have been a three-hour journey.