Ok, some self-defense stuff here.
If you are in a position where your life is threatened, then you must act as if the person is willing, even eager, to take your life. You must also act like he is a blackbelt in all martial arts, trained by the Navy SEALs, the Marine Corps, Spetsnaz, some ethnic martial arts master, and Mike Tyson's Punch Out. Oh, and he has three friends who are just as skilled, and hiding behind you.
In short, you've lost.
So you must give this person no chance to take your life. You have to evaluate the situation and either comply or strike quickly and without hesitation. You should comply if you are reasonably sure that you can get your way out of this--this means you have to know what he's thinking. I mean that you know exactly what options he's considering, and which he'll probably choose, and for what reasons.
If you have a momentary advantage, you should strike. Decisively. Killing is acceptable. Half-measures like "shooting him in the leg" or "run up and disarm him" or such should be practiced beforehand and used only if the opportunity really, really presents itself, as they generally don't work. Also, don't worry about the legal implications. In short, don't fight to wound--fight to kill or get away.
Otherwise, a compliant stalling is the best policy.
If you're striking, the point to stop is when he won't fight back. Him falling down is a possible indicator. Don't trust him til you've secured him and removed his weapons or confirmed that he's dead/unconscious. Even then, keep whatever weapons you can find on hand.
Remember, if you're in a position where this advice is helpful, you've already lost. Yanlin's advice about public signs and cameras is excellent--it'll push you out of any casual criminal's hit list.
Mo' info. This said!
If the reporting is accurate, then the guy's actions show that he did not believe that the victim would fight back after the first bullet. He's guilty of some sort of murder or manslaughter.
I'd like to point out to everyone that gun control or gun ownership doesn't solve this problem--criminals are made from people who were abandoned, or have been in a very desperate situation for a long time, not from the availability of guns. Good parenting and low poverty will help a ton more than gun carp.