JAKE TAPPER, ABC NEWS: Philosophically, what separates an act of violence from an act of terrorism?

PRESIDENT BARACK OBAMA: Well, look, we -- we have seen, in the past, rampages of this sort. And in a country of 300 million people, there are going to be acts of violence that are inexplicable. Even within the extraordinary military that we have -- and I think everybody understands how outstanding the young men and women in uniform are under the most severe stress -- there are going to be instances in which an individual cracks. I think the questions that we're asking now and we don't have yet complete answers to is, is this an individual who's acting in this way or is it some larger set of actors? You know, what are the motivations? Those are all questions that I think we have to ask ourselves. Until we have these answers buttoned down, I'd rather not comment on it.