An altercation (at minimum popcorn) ensued, and Reeves fired his weapon once (per Pasco Co. sheriff). The single shot injured Oulsen's wife in the hand, and penetrated Oulson's chest, killing him in short duration. An off duty Sumter sheriff's deputy detained Reeves until local LEO arrived.
So just following standard police training, I guess.
(Sad to say, I'm not sure if I'm being sarcastic or not.)