While we, the people, demand gun control, politicians act in their own self-interest, as little kids rehearse their own deaths in school drills until the day comes when it is no longer practice.
Gun laws must be changed. However, horror is also a symptom of our broken society. Americans are driven by their dysfunctional institutions and postures of constant aggression. All this antagonism toward one another leads to hatred, which leads to violence. When you combine it with our lax gun regulations, you get senseless carnage.