He clearly fired three rounds. And you can clearly hear that sound so feared by folks in places they should not be, doing things they shouldn't be doing, the sound of the action of a pump shotgun. Nothing else quite like it.
Most lever actions make the same noise!
Yes, agree with your comment. It clearly was three shots.
My not-so-well-explained 2 for 2 comment was that he bagged two out of two perps. There have been so many stories of gunfights with police involved where they fire a multitude of shots without achieving the efficirncy of this guy in the kill ratio.
Then again, having a pump shotgun at this kind of range helps to lessen the errors made.