Really does not matter. This morning on the news indicated perhaps a runaway train. That could mean cars themselves drifted and perhaps were derailed by a derail mechanism. Nothing can be ruled out at this time including foul play.
Let the Canadian Transportation Safety Board do its investigation, then we will know what happened. That could take a year or so.
Nonetheless, full condolences really from the heart, to those impacted by the accident.
Yes, originated on CPR. Train was tied down with brakes set. There was a fire on one of the engines at 11.30 which was extinguished, but power was shut down. The brakes would have bled off by 01:15 after the locos were shut down and if there wasn't a sufficient number of hand brakes applied to the train without air brakes, it would have allowed the train to roll since it was left tied down on a grade. Apparently, this was one of MM&A's infamous one man crew jobs which seems insane to me with a commodity as volatile as oil.