IF (Big IF) there had been men (and women?) that had of immediately rushed the shooter, the death toll would have probably been 1/4th as great.
But who wants to be the first to charge into fire?
Only those that know the facts and most people are unaware that such Shooters are basically wimpy, woosies and would run the instant they were attacked (even by unarmed people).
But who wants to be the first to charge into fire?