Justified or MURDER

Gault shoots at Rambo while he is hanging from a cliff. Can the police kill an unarmed man just because he is "on the run" and get away with it as a justified shooting?

A short while later the Sheriff and all the deputies are yelling at Rambo from the top of a cliff.
He is unarmed and has his hands up. The only thing he does is take a couple of steps back and argues with them a little bit. And they all open fire on him. Again: Can the police kill an unarmed man just because he is "on the run" and get away with it as a justified shooting?

Now, some of them may realize they did something wrong and try to cover it up, but, in the movie, except for David Caruso's character and the helicopter pilot, they seemed to believe they were doing the right thing.
So, assuming that they told the story exactly as depicted on screen, except that they kill Rambo instead of him getting away, would they have been charged with Murder?