To summarize current information, the
lead unit was kept running - presumably to maintain trainline pressure -
not to keep the brakes on (as quoted in the press) but presumably to maintain the train line pressure so the outbound engineer could do a simple continuity check and go. No informed railroader would leave a train unattended on a grade expecting the automatic air brake to be sufficient. The lead unit had the fire that attracted the attention of a nearby resident who called the fire department. We have not heard anything about locomotives being moved during the emergency response.
One thing that was interesting about the briefing that accompanied this presentation was the fact that Transport Canada said they did not know the speed of the train at derailment. (We've seen speeds quoted in the press.) That suggests the fire department may have pulled the main battery switch cutting out the event recorder. See copy of report delivered to the Rail Safety Advisory Committee:
Transport Canada Report