As NRA folks are fond of pointing out, if guns are banned, those who want to kill others will use other methods. By and large, guns do a better job than most others, but even without guns, you still see knife attacks (usually with dramatically lower casualty counts), vehicle attacks (which can be comparable), and bombings (which can be comparable). On top of that, banning guns altogether creates other issues, not least of which is the fact that there are a lot of guns in the US and you'd inevitably end up with a whole lot of non-law-abiding people making things very dangerous for those that gave theirs up.
Ultimately, having guns around isn't inherently bad, it's just a matter of keeping them out of the hands of people that would do harm with them and identifying those that are at risk of causing harm with or without guns. Every gun sold should require a criminal background check, safety certification, and recent psych evaluation, as well as a mandatory two-week waiting period (which has been overwhelmingly demonstrated to significantly reduce suicides by firearm). Every gun owned should be effectively secured (with ammo secured separately) at all times when not in use (carrying counting as "use"). Gun owners need to be held legally accountable for ensuring that guns are not used by unlicensed users, including assigning some liability for any crime committed with their gun if it has not been reported stolen (and even then, if it's stolen because it was inadequately secured, there should be penalties for that negligence).
Will these measures fix the entire problem? Obviously not. But that last point in particular would go a long way toward stopping teenagers from taking their parents' guns and shooting up schools with them, which accounts for many school shootings, and mental health assessments and waiting periods are critical for keeping crises from driving people to commit gun violence. On top of that, there need to be better mental health supports all around, including anti-bullying efforts (in both schools and workplaces), for the sake of preventing those crises from happening in the first place.
Do you have an opinion on why a person might kill themselves vs. a violent outburst?
Anecdote,
There was a guy at my high school nicknamed "twist". I played on the same football team as him, but never really interacted with him. All I remember is that he was kind of a dick, but wasnt bullied. He was mostly just left alone.
He ended up shooting himself, so he obviously had mental health issues and access to a gun. So I wonder why he didnt attack the school. Would that change today?
Are a lot of these shooters today people that would have gone quietly 20 years ago.