The emergency services said that the local train was travelling from Nimes to Montpellier when it hit a tree that had fallen across the track near Saint-Aunès, east of Montpellier.

They said that a violent thunderstorm brought down the tree, which also damaged the electric power cables over the tracks, halting all services on that line.

One critically injured person – who witnesses said had been thrown from the train – was evacuated to hospital by helicopter.

Officials from the rail operator SNCF said the train was carrying 250 passengers and would have been travelling at 140 kilometres an hour (87 miles per hour) at the time of the accident.

SNCF said firefighters and police were at the scene, but access was very difficult and made more so by the thunderstorm and hailstones.

The accident happened at around 15.45 CET. (Euronews)