Investigators suspect that a train derailment in northwest France which injured 44, one gravely, was the result of sabotage, a police source said on Saturday.A fragment of rail was found on the track, with the possibility of a malicious act being treated as the main line of inquiry as a result, the source said.Carrying 186 passengers, the train was running between the Normandy cities of Rouen and Caen when it derailed around 7.45pm local time on Friday close to Renault’s factory in the town of Cleon.Authorities activated a mass-casualty response plan, with 130 firefighters, five medical teams and 80 vehicles drafted in.An AFP photographer saw a mass of railway staff working around the train on Saturday morning.A derailed train carriage in Cleon. The train was running between the Normandy cities of Rouen and Caen when it derailed around 7.45pm local time on Friday. Photo: AFPRouen prosecutor Sebastien Gallois said 44 people were injured including an 18-year-old woman evacuated “in a critical condition”, while tests for drugs and alcohol on the train driver had come back negative.