From the washingtonpost.com, I think " … in the aftermath of a mass gun crime, the same ritual: national shock and anger, traumatized communities asking how this could happen … "
I’m thinking that perhaps many of the how and why questions are rhetorical or a purgament, a communal expression of complete and utter frustration and helplessness.
If one really wants to study these things, like a college student might want to study something may I suggest renting Netflix: 71 Fragments of a Chronology of Chance. This is not for everyone. It is hard to follow - but real quality if one can follow it.
Many may not like it.