[SecondAmendment]

I’ve read that the firefighters turned OFF the lead engine, which was providing power to the air brakes.

This makes no sense to me.

As I understand it, the air brakes require air pressure TO DISENGAGE THE BRAKE PADS, so that any leak or loss of pressure would always lock up the brakes by design, for safety reasons.

So I think sabotage is very likely, eh ?

[Izzy Dunne]

Hmmm. I hadn't thought about it, but you're right. Cutting the power should have ENGAGED the brakes.

Here's the story I read.

so firefighters shut off the engine to stop the flames from spreading. That slowly disengaged the air brakes,

That DOES seem wrong, doesn't it?

[thackney]

The brakes are actuated on a reduction in pressure, but the motive force for the application of the brakes comes from an air reservoir aboard each individual rail-car, not from a spring.

Info by FReeper Mycroft Holmes:
http://www.freerepublic.com/focus/f-news/3040657/posts?page=27#27