French authorities are investigating whether a passenger train derailment near Cléon, south of Rouen, on Friday evening was caused deliberately, after prosecutors said a piece of rail found on the track was the likely cause. The incident injured 44 people, including an 18-year-old woman airlifted to hospital in a critical but now stable condition, and prompted a large emergency response. The investigation matters because it raises the possibility of sabotage on France's rail network, though officials have not confirmed this and stress the origin of the rail fragment remains unexplained.

The train, travelling between Rouen and Caen with 186 passengers aboard, derailed shortly before 20:00 local time (18:00 GMT), prompting a response from around 140 firefighters and emergency workers. Prosecutor Sébastien Gallois said the train's black box had been seized, a court-appointed expert engaged, and interviews scheduled, while the driver tested negative for drugs and alcohol. A passenger described windows shattering and track debris entering the carriage as the train shook violently before coming to a stop.