Ok, start with this:
Will the left acknowledge that their liberal policies of the last 40 years have led us to this juncture? Mass shootings were never an issue despite the millions of guns floating around for a century or more. What changed: breakdown of the family; lack of fathers; marriage to government; eradication of God; lack of respect and values; drugging rambunctious children; addiction to violent video games; social media. The heart of the matter lies within those elements; elements that have overtaken a large segment of society.
Until those issues are addressed and corrected, we must secure our schools and other places of gathering. Posting wussification signs such as 'Gun-free Zone' are not just asinine, but inviting to the disturbed.