It's got to be either the Nantes FD or some saboteur.
Though I still can't comprehend how the tank cars got to town before the locomotives (which apparently never arrived) since that was the direction of travel of the train.
“According to the railway, the trains locomotive was shut down subsequent to the departure of the engineer, depriving the trains air brakes of the power needed to keep the load from careening downhill.”
I’m surprised these brake systems aren’t designed like trucks where the air keeps the brakes OFF. Failure of an air line or compressor would mean the brakes lock up.
While I confess that I don't know the mechanics of train air brakes, I thought that a positive pressure released the brakes and that if there were no pressure (as would be the case if the engine's compressor was NOT running), the brakes would be locked.
I'm assuming that this was a fail-safe system designed to stop cars from rolling if they got disconnected from the rest of the train.