If I had the ability to kill them, I would instead rob them, taking their assault of a harmless creature as a sign of their own innate weakness. If they had nothing of value, I would leave them unharmed or slightly injured to avoid legal repercussions. I doubt I would get emotionally involved, in situations like these I look for the outcome that leaves me in the best possible state of affairs. Killing them brings me nothing but experience in killing (which, from the givens, I probably have enough combat experience), and could land me in prison for three murders. At best, I could attempt to plead temporary insanity and be confined to a mental institution for a period.