Off the top of my head, I can think of two mass shootings that were mitigated by armed civilians: http://en.wikipedia.org/wiki/Charles_Whitman http://en.wikipe

Off the top of my head, I can think of two mass shootings that were mitigated by armed civilians: http://en.wikipedia.org/wiki/Charles_Whitman http://en.wikipedia.org/wiki/Charles_Whitman http://en.wikipedia.org/wiki/Appalachian_School_of_Law_shooting http://en.wikipedia.org/wiki/Appalachian_School_of_Law_shoot...