I have to ask, what ordinary people would not get alarmed by a guy walking into a crowded area wearing a Respirator, a body armor suit, a cape, and caring several weapons under his arms?
Granted the long guns can be hidden, not easily, but possible, and the pistol? All added up you got a over bulked 300lb man coming in. Either he was there before, or the supplies we hidden there fo his use.
Motive: Having failed out of Medical School, Not being able to connect with people, being mad at classmates. Crazy, NO, absolutely not, just a very bitter human, Anger is the motive.