Video just after it happened
3 dead, multiple injured, after an Amtrak train derails in Montana
https://rumble.com/vmyyj9-3-dead-multiple-injured-after-an-amtrak-train-derails-in-montana.html
May or may not be relevant, it appears that there was maintenance planned on that section (piles of new ties beside tracks). Also looks to me as if splitting a switch was possible as the trains appears to come from the far track onto the near track then back to the far track in that video.