"OUTRAGEOUS" - I have seen the shooting down of two Presidents, a bunch of peaceful demonstrators at a college rally, the shooting death of two candidates for President, the curbside murder of a peace-loving musician named Lennon, the wiping out of several rap stars, and now suddenly this act was "Outrageous"? Hold on, it seems quite "in-rageous" to me. Quite fashionable in our country, actually.
"SURPRISING" - Anyone who claims to be surprised by this act is a simple liar. No one is surprised by gunplay anymore, or the murder of prominent people in the country. All of it is perfectly foreseeable, if not the specific target, at least the act.
"UNEXPLAINABLE" - Anyone who claims not see an explanation for this lacks the simple level of perspicacity to see the connection between cause and effect. If you take an emotionally disturbed person, give him high powered guns, inspire him with vitriol, then you are going to have murder. How's that for an explanation?