Imagine this scenario: A serial killer is pointing his gun at an innocent person John and wants to kill John. An arahant is near the killer and knows that the killer will kill 5 more innocent people after he kills the innocent person John. The arahant can choose to kill the killer before the killer kills John and the other 5 innocent persons. Would the arahant kill the killer? Would a Buddha kill the killer? If yes, why? If no, why?