A minute of silence was held at noon 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. Formal identifications of the bodies were underway, the source said.
The accident was still causing disruptions on Paris commuter lines on Saturday, while the Paris-Austerlitz station, where the train had departed from on Friday, was expected tor remain closed for several days.