We aren't discussing this particular shooting, but the topic of school shootings in general.
In my opinion, we don't don't do much of anything. We can't innoculate ourselves from every kind of nut job.
By the same token, I also don't believe we begin coating our trees with tectured, non-splintering plastic and safety steps so that children don't die from falling from trees.
Schools are slammed with burdens.... we have all kinds of aggressive, diva, thug-like kids that you never hear about (because they are protected by HiPPA) and they go to school with your kids. Teachers and admin are dancing on eggshells to keep those bad boys happy, too... it is horrible.
It is politically incorrect to segregate the bad kids from the good, so we are stuck.
Schools are broke. Not sure if every single school can be outfitted with special security features.