So I'm gonna describe what I see from a second opinion here, he walks in from of your car and stops you beep the horn and not a second late drive I to him (he didn't move into your car) you get out, he gets up pulls out a gun because when you are ran over it resets your ammo and takes it off safety, doesn't threaten other than maybe pointing at you however he puts the gun away and doesn't engage with you. He gets ran over and do does the shotgun guy you wait for them to get up killing the guy you ran over and the shotgun guy who never threatened you or even took his gun off his back. I do not see a real reason to kill especially the guy with the shotgun as he didn't even threaten you at all.