chicharrones
needs more ammo
From a strategy perspective the first shooting action was clear. The rest to me seems driven by the anger both at having to shoot at all, plus finding out the perp was using a look alike gun.
As to what course an armed robber will take after taking the money only speculation can take place. He could kill to eliminate witnesses.
I thought of that probability the first time I saw the entire unedited video. Easy for me to understand, whether wrong or right.