What a sad sad day.
Even countries with gun control have instances like this (but they're arguably less frequent), and some countries with lots of guns have almost no problems like this at all (Switzerland for instance).
Just trying to imagine dropping a grade school kid off at school to find them dead in the afternoon from an insane thing like this I find that I can't do it, it is just too far from what I can still imagine. And I have a pretty rich imagination...
This world could be so nice, why does it have to be such a crappy place?
Nice stuff happens. It just doesn't make (or sell) the news. But that doesn't mean the world isn't nice.
When you have a population size of 300 million you're going to get a lot more outliers (crazy people) than if you have a population of 7 million. Statistically, you will also have crazier people.
So consider the EU, with a roughly equivalent population.
Statistically, once you hit a few million people, you've got enough people involved that the proportion of outliers has stabilized pretty well.
Switzerland is interesting in many ways, one of which is the degree to which the government is very close to a true democracy, the fact that they don't waste a ton of money on their defence (which has a lot to do with them being in a geographically special position) and in the way that they have guns but abuse is low.
The fact that this is very different to the situation in the US might hold some clues to what could be done about this.
My family home schools our children. It coincidentally helps solve this particular problem. (Perhaps it also reduces the likelihood that we spread viruses like the flu).
Making public education more distributed by the use of technology could certainly help with security.
1. Easy availability of guns 2. Lack of a family based society. In my opinion, insanity gets aggravated by loneliness
I don't believe the shooters are mentally ill. There is simply sad, evil people in the world that think that shooting a lot of people will get them some attention/fame/recognition. In a society like the current U.S. society where being unknown and alone is worse, in the mind of some people, than being known as a serial killer this kind of thing is bound to happen.
Due to the nature of your society, you will never ban firearms. They will always be available and those wanting to kill can always find another ways.
In mu humble opinion, your problem lies in the fact that some very weird and sad people there find that serial killing is a glamorous life/ending. The worship or desire of a thug life or being known/recognized as a criminal by the media and society drives these wackos towards this behavior.
When consumerism is king and money/oportunity/perspective is low, when not being the most popular thing ever is worse than dying, when parents don't impose limits to their kids and just keep pumping meds into them, this disaster will keep happening.
Even so, this represents, very optimistically, a dozen or two hours of interaction with others a week. It cannot hold a candle to the interaction children going to schools experience.
But when it comes down to it, if a crazy person can easily get a hold of a gun, then there will be more shootings. There are two requirements for shooting sprees, 1. Crazy person, 2. Easy access of guns. Try to limit both.
I can only speak for my family, but we spend lots of time with other families and children. Church, Boy Scouts, Soccer, etc.
Ask yourself, have you ever been in public and recognized a home schooler because of the way they act?
The inverse is true too, how many socially awkward people do you remember from your public schooling? I sure remember a lot.
From my personal experience, I don't see a relationship between home/public schooling and social relationships.