Those who want you to doubt that anarchy (self-ownership and individual responsibility) is the best, most moral, and ethical way to live among others are asking you to accept that theft, aggression, superstition, and slavery are better.
How to solve the "mass shooting problem"- or any other social (or, rather, anti-social) problem:
Make the Zero Aggression Principle normal and expose any and all exceptions. Don't excuse violations by anyone because of their "job", position, or office.