The most extreme type of modern train theft occurs when thieves cut the air-compression brake hoses that run between train cars, thereby triggering an emergency braking system. When that happens, the engineer stays in the cab and the conductor walks the length of the stopped train, trying to locate the source of the problem. (Thieves can also stop a train by decoupling some of its cars.) Of course, if a train is miles long, that walk takes a while. In the meantime, the pilferers unload.
Way more brazen than I had imagined. I was foolishly just thinking these were people sneaking into train yards at night.