Walter E. Williams recently wrote an article entitled "Past versus present Americans" in which he asks what is different between the past and present concerning guns? It's the people who have changed.
In the past, he points out the greater access to guns and the lack of school shootings. Talk of armed police in schools was nonexistent. What changed? My theory is, as the idea of moral relativism became the norm, we stopped teaching morals and respect for authority in schools and our homes.
God and respect for authority became quaint things of the past. In reality, these things and family are the foundations of our society. The left says that teaching Judeo/Christian morals is "unfair" to other religions. Sorry, Judeo/Christian morals are universal morals and values that have given this country the freedoms and prosperity we have today.
Not teaching morals in schools, not teaching about God and heaven and hell, not teaching patriotism, not teaching respect for authority are all taking our society down the toilet. Until we start teaching these things in school, you can expect more gun violence.