They got spooked when he moved and they should have been able to realise that they held every advantage and that there was time for another play. He wasn't going to run at them faster than a bullet. Missing leadership, experience ?.
How do you make that decision in real time? It's not a turn based strategy game. They aren't trained to take shots like that.
I'm not defending them either. It looks like a poorly handled situation. To me it doesn't matter whether 1 shot or 48 were fired, they should have tried to de-escalate the situation and they failed. Is this situation better if he's killed by 2 cops instead of 6?
How do you make that decision in real time ?. By not getting spooked. Experience, leadership by someone in the group. He's not going to run at them faster than a bullet. There was time for another play besides yelling at him which with the dog and everything obviously had no effect.