Accounts of the families that lost loved ones in 9/11
This is why I don't think killing is ever justified. Look at all the pain and suffering that one person's death can cause. Now think about the thousands that die in war. That's too much suffering.
Now, if a man has no family; no one who will miss him if he is gone (and the same goes for me, because I wouldn't want to cause MY family grief either), then if he wants to risk his life fighting me to the death--bring it on. But otherwise I couldn't morally kill someone for any reason.
PS. And let's leave self-defense and rage out of this discussion, we've learned that primal instincts can easily override moral beliefs.