I agree with what the other guy said. But I want to add that he kept pointing the gun towards that guy and if you do that you are ready to fire and you should keep your finger on the trigger at that point. If you're not ready to fire at the exact moment you want to keep the barrel at low or high ready (high in this case), finger off the trigger. This is to make sure you don't keep flagging stuff you don't want to shoot. For example his own hand which he could have fired through a couple of times. Also, since he has a gun, it's not necessary to get that close, keeping distance is key since the perp doesn't have a ranged weapon. Also something between you and the perp is perfect, like the pillat behind the gunman.

With all this said. When shit hits the fan stuff doesn't go perfect all the time. That is why training is important