In my books if you shoot anyone its murder, you physically pull the trigger, you mean to do it. To me it sounds more appropriate.
It's supposed to be 2 guns, last i heard, so obviously he wanted to go and do something. He supposedly had a gripe with a fellow taxi driver, so if he goes and shoots him, what else can he do in his view. Locked up or top himself he has now gone too far, and pushing himself.
He was supposedly asking folks for directions then just shooting them out of his rear passenger window. The taxi man is supposedly the person to kill, the others....... hope they rest peacefully.
Obviously he was upset about something, again I wont say rumours, but I think in the end the system failed him, he must have been desperatly upset, depressed, or some kind of mental Illness going on.