The CAMPUS NEWSPAPER reported two 9mm handguns. That HAS NOT been confirmed, by ANYONE. Witnesses stated he had a vest with several magazines (actually they said "clips"). Witnesses stated they saw ammunition BELTS. Right now they don't know who the guy was, and they haven't confirmed identification of any weapons. So any assumptions are just that, assumptions. Why don't we WAIT and get some FACTS, before anyone rushes to judgment?
If you're the ONLY person armed, all you need is for your victims to be paralyzed with fear, and to have ammunition. IF he had two 9mm handguns and several 12-15 round magazines, he wouldn't need a rifle of any sort. Besides, I doubt he had access to a select fire full auto military rifle.