This is sad news. I've seen engine 4001 "The City of Wall" a few times while I was living up in South Dakota. What was the lead engine?
This kind of reminds me of a story of when I was in Rapid City. A train of hoppers (full of cement) got loose and rolled through town. They ended up on a dead end siding. The train cars jumped the track at the end and kept on rolling. They rolled across a street where a couple of them ended up on their side. The road was closed for a day or so. Fortunately they were able to save most of the train as the cars cut their own rails into the cement road, so as the locomotive could pull them back onto the track. Surprisingly, no one was hurt, but what a sight to see!