There is another aspect of this that have difficulty reconciling...
(I have tried to find stats on this, but different types of multiple shootings stats tend to be added to one another so it is difficult to pin down the specific Columbine type "Mass Shootings" that are not otherwise associated with other criminal activity (Robbery/gangs/etc)
Sooooo.
A) These incidents are
common because they seem to happen a couple of dozen times each year or so...
B) These incidents are
rare Because (In a country with 350 million population, woeful mental health services with openly psychotic nutters wandering the streets, where gun ownership
comfortably exceeds smart phone ownership and where Gun shops outnumber McDonald burger shops
Four to One, ) they
ONLY seem to happen a couple of dozen times a year or so...