Some kids are abused, and many suffer teasing at the hands of peers. Some kids have psychiatric illnesses such as schizophrenia and schizotypal disorders. A few people are psychopaths. Despite all of this, very few kids commit horrific school violence that includes homicide and/or suicide. In order for this to occur, several factors must coalesce: psychosis or trauma, antisocial personality disorder, sadism and/or self-loathing. Also, weapons must be available to the perpetrators and they must know how to use them.

People with antisocial personality disorder (eg, psychopaths) sometimes commit despicable acts despite the fact that they emerge from loving homes. Traumatized individuals can commit serious violence if they are deeply immersed in fantasy worlds. Their home lives bring them only pain and suffering, which can transform into rage that they aim at their school.

Unfortunately, all too commonly, the friends and parents of school shooters ignore the warning signs. Peers have dismissed the plans of the shooter as false, since they have been lied to many times before. In addition, the shooters, especially ones suffering from psychosis sometimes carefully concealed their problems from the world, desperate to avoid the stigmatic labels that come with admitting "craziness." These kids wanted world to bend to their will, and they became enraged when it refused to do so. 

Some of the shooters were narcissistic, obsessed with fantasies of mutilating animals and/or humans and deeply involved with violent video games. However, any one of these factors alone would likely not produce a deadly shooter. It was the individual psychology of each person combined with a deadly cocktail of factors which led to horror and human tragedy. Luckily, some school shootings are averted by the bravery of someone who speaks up about deadly plans that they hear and disturbing behavior that they observe. These heroes are protecting society from unspeakable violence.

How To Prevent School Shootings 

Lesson 1: Privacy is Limited to Protect Others
Lesson 2: Do Not Lie to Protect Your Child
Lesson 3: Follow Through With Due Process, No Matter Who is Involved
Lesson 4: Pay Attention if the School is Concerned About Your Child
Lesson 5: Eliminate Convenient Access to Firearms
Lesson 6: Take All Threats Seriously
Lesson 7: Everyone Can Stop School Shootings
Lesson 8: Recognize Rehearsals of Possible Attacks
Lesson 9: Punishment Does Not Prevent Attacks
Lesson 10: Security Cannot Provide Complete Protection

Why Kids Kill: Inside the Minds of School Shooters by Peter Langman, 2009

This is a most excellent book written by a clinical psychologist who has an extraordinary understanding of human psychology. I learned much about mental illness and human motivation and behavior. 

• Books about school shootings
• School Shooting web site