At one point, one of the troopers (Seiple, I think) picked up what appeared to be a handgun and tossed it away from the scuffle. I couldn't see whose gun it was or where it came from. Yet both officers had guns to return fire when Clary (the perp) grabbed his gun and started shooting. Certainly hectic and confusing but, in the end, I agree that the troopers delayed firing too long.
Shooter didn't have a very imaginative defense.