French investigators say it could take up to three weeks to identify all of those killed when a bus and a lorry burst into flames after a head-on crash near Bordeaux.
Authorities have begun analysing the charred wreckage of the tourist bus, which collided with the lorry in the village of Puisseguin.
The crash killed 41 passengers on the bus, mostly French pensioners who were on a day trip to the wine-producing region of Bearn.
Eight of the passengers survived after motorists smashed windows on the burning vehicle to free those inside.
The lorry driver and his three-year-old son also died.
The boy's body was discovered some time after the crash, after relatives told authorities he must have been inside the lorry.
A few miles from the crash site is Petit-Palais. 28 of the victims came from this tiny hamlet.
One of the villagers who died was the former mayor and the chairman of the pensioners group who organised the trip.
The current mayor, Patricia Raichini, has lost three of her sisters-in-law.
Four survivors are in hospital and in a critical condition. Two have severe head trauma and two have severe burn injuries.
The bus driver has been released from hospital.
He has been hailed a hero for managing first to open the door of the bus and then managing to help some of the survivors from the vehicle.
He knew many of them personally. He is now helping police to understand what happened.
The road is known as a black spot for accidents but it was resurfaced in 2011.
According to regional officials, all the signage and warnings were present and clear for drivers to see.
Christophe Auger, the prosecutor for the nearby commune of Libourne, said it is "impossible at this stage" to determine what caused the crash.
Mr Auger said the investigators' main priority over the coming days will be to identify the victims, a task made difficult by the charred state of their remains.
From aerial footage it appears that the lorry jackknifed and the bus hit the front of the trailer.
Inside the small community hall in the neighbouring town of Puisseguin 43 candles have been lit.
Each has been placed on top of a wine barrel to represent the 43 who died.
This is the heart of one of France's best known wine regions.
Through the night and into the morning relatives have gathered to place photographs on the barrels, next to the candles to remember the dead.
