"Once Upon a Time in the West": who killed who?

Who killed everybody on Morton’s train? Who shot Cheyenne? I thought for years that Cheyenne was put on that train, and he and his henchmen killed everybody escaping. But I saw it again today, and now I don’t think so. Morton’s train was sitting out in the desert somewhere, not in town where the stuck Cheyenne on a train sa a prisoner. And this version had Cheyenne’s death scene, which had apparently been cut out of the original American realase. He talks about a “madman on the train”, which might be Morton, but it sounded like Cheyenne said “Mr. Churchill” shot him. Who the hell is that?

And if they killed each other. how the hell did they meet?

I don’t remember, but I saw it again not too long ago and remember not being confused about that scene. Watch it again; maybe with commentary.