What’s with the abandoned train near Valentine

So, I just left camp, and there's a train abandoned on the track right outside of the forest. It has two passenger cars, a mail car, and a caboose. There is nothing in the train except a few bits of trash. All the containers are left open as though it was recently robbed, and I can't figure out what happened. I'm afraid to try and drive it, because I feel like it's a trap.