But is it really the genesis of a killing spree of this magnitude? I don't know.
Since we're talking of hypotheticals would a crazy, right wing, neo con, gun nut, in possession of a firearm have trimmed the death count? But that's not even part of the discussion.
But, apparently one fact is concrete; he killed people continuously for an hour. It appears at this point no one defended themselves. Why? Where were the police with all their powers and fancy weaponry? Perhaps the option of legal defense should be available, during the fact, not after, when excuses are luxuries.