Prediction is a lot easier then prevention. As regards the "outbreak" of school shootings several common factors link the episodes.
The perpetrators are seen as loners who "don't fit in". They often adopt a "Goth" style of dress. They are the subject of ridicule from the "social" and "jock" cliques and tend to associate only with other "outcasts". They are secretive and spend an inordinate amount of time playing video games. They are often on the high end of the bell curve but avoid displaying their high intelligence. Most importantly, they are often receiving prescription psychoactive medication(s).
I believe the two most important characteristics are the video games which create a false reality and the psychoactive drugs which have serious side effects (deep depression, suicide, extreme anger). The increase in the number and severity of school shooting incidents correlates with the increasingly common use of powerful mood altering drugs. Not every child exposed to these drugs displays adverse symptoms and in many cases the symptoms only become apparent when the drugs are abruptly stopped and the child is left to cope with withdrawal cold turkey.
This needs further study before we allow politicians to stampede us into blaming inanimate objects for committing mass murder. Dumbing down our children is bad enough, now the new normal is doping them up.
How do you punish someone who kills himself?