Every time there's a shooting, everyone uses emotion to say everyone was right and everyone else was wrong. "More killing, so all the rest of you should agree with my politics, dah!" It started with attitude. Mass shootings only indicate an already-divided country. People either demand guns everywhere or guns denied or some combination thereof; no one argues in favor of training the militia.
The Second Amendment guaranteed the right for all to own and carry firearms because all were obligated to be trained in the militia. Liberals want none of it and so-called Conservatives want the arms with not a single word about militia training for all. But, militia training for all citizens would solve the problem, both the attitudes of potential shooters and the readiness of the general public. People with "mental problems" wouldn't be allowed in the militia and thereby wouldn't be able to own firearms. Denying weapons to the insane and unstable in that way would calm concerns of the Right.
The Right is concerned that the Left wants to force the Right to behave like they are part of the Left. With recent laws that punish people for not agreeing to LGBTQAYKXYZYTBA speech patterns, who can blame them? With Universal Studios' The Hunt even having been filmed, who can blame the Right for feeling the need for self-defense? Still, we don't need massive gun ownership without training; we need the militia for all people. The militia is what the Right-Wing's precious Constitution calls for, but the Right-Wing has not. So, their fear of the Left, however justified, is well-earned.
Even in a Liberal utopia where everyone is filled with hatred, while all means of acting on such hatred have been removed, no one would be safe without public-wide training. The whole public needs to be trained to deal with every dangerous scenario, from a dictator's takeover to an invasion to a mass shooting. It's called the "militia" and it's the one thing neither extremist nor moderate of our polarized political spectrum even peeps about.