All acts of public violence (violence broadly on the public body[1]) have the same root causes -- the purported politics and manifestos are just window dressing; the ideological last straw.

Sad people without identity or purpose, lacking hope, but bearing a heavy grudge and a simmering rage. If you want to make it stop, you've got to address the root; and at the root are tough issues of social justice, economic development, and civic organism.

[1] school shootings, workplace shootings, baseball shootings, mass stabbings, concert bombings, church shootings, train knifings, etc.