Except in very rare circumstances, as in mechanical failure, guns “don’t just go off”. Someone’s finger was on the trigger, And actuated it.
Yes, of course. We don’t know who’s finger was on the trigger. Presumably the person who pulled it but that’s just a guess. I can imagine the intended victim grabbed and twisted his hand and arm, causing the trigger pull.
Gun safety - don’t put your finger on the trigger unless and until you’re going to fire it!
There is more to this from reports I’ve heard or seen... that the man was highly aggressive. I don’t know what his intentions were or why he needed a pistol for this situation. A little scuffle between two men doesn’t seem to warrant the pulling of a gun. And armed robbery on the packed train car doesn’t make a lot of sense either. But I guess if he was thoughtful and conscientious he wouldn’t have a hole in his head right now.