Apparently his name is Vester Flanagan, on-air he went by Bryce Williams. Here he is with one of the victims.
He seems to be tweeting right now: https://twitter.com/bryce_williams7
People are saying that he legit just posted a video from his POV of the shooting. Can't confirm as I'm not in the mood to watch that sort of shit, but check that Twitter feed if interested.
EDIT: I caved. The video is real. Holy shit.