“There is a video in the link exactly how it happened.”
The video says that when the locomotive shut down the air brakes lost pressure and ceased to brake the wheels.
I though air brakes worked the other way, namely, that pressure was what released the brakes, so if there was a pressure failure the brakes would be applied.
What have I missed?
Apparently, air brakes on locomotives are opposite from air brakes on tractor trailers. This enables them to move trains/cars around in railyards.