The logical way to study and find solutions to Mass Killers of Strangers/Innocents, would be to look at each by looking at the Individuals Life, working backward until we see the Common Denominators occurring over and over in these cases. Along with the use of the Death Penalty afterward as a Deterrent.
Yet even as We would do so and make a drastic drop in these events while maintaining Our Founders foreknowledge with the Second Amendment, this all still Never sits well with the Segment in Our Society which doesn't care about setting things straight, or
the Lazy Ones who 'Go Along to Get Along' ! Their deepest interests lay in Creating a Dictatorship where Our population has no way to fight back.
That scenario of course would Kill a Vast number more Innocent Americans than many Mass Shootings, by way of what Dictators do to stay in Power, today and have done in the Twentieth Century for example where the Peoples Arms have been taken-away !
Even though they, like the rest of us have lived the highest lifestyle of all Peoples that have ever lived on earth under Our Elected System of Government, They Will have None of It .