It's every parent's worst nightmare: "Shots fired at XYZ School; several students injured."

It's every parent's worst nightmare: "Shots fired at XYZ School; several students injured."

Parents with children at the school are mortified, unable to think clearly; all they want to do is get to their babies. Other parents are thankful their children are not at the school, yet they immediately empathize with the parents affected by the tragedy. Everyone hugs their kids a little tighter that night before they go off to bed.

After an incident, the questions begin to roll in as the nation comes to grips with the reality of what has occurred. We ask, "Why?"

Did the shooter just snap? Did he or she know the victims? How could someone this 'sick' still be allowed to walk around amongst us? Why are all of these shootings at schools happening now? What can our schools do to prevent these terrible crimes from occurring?

Understanding the history of school violence is important for us to get a feel for where we are today and where we should be headed.

School violence is not a recent phenomenon. Violence has been occurring in our schools since schools were created. The single, most deadly act of school violence in U.S. history occurred in Bath, Mich., in 1927, when the school board treasurer, Andrew Kehoe, blew up a school, ultimately killing himself and 44 others, including 38 children, because he blamed the school system for causing him financial harm.

The list goes on: Charles Whitman, the University of Texas at Austin tower sniper in 1966; Kip Kinkel at Thurston High School in Oregon in 1998; Dylan Klebold and Eric Harris - the Columbine High School shooters - in Colorado in 1999; Cho Seung-Hui at Virginia Tech in 2007, to name just a few.

No real profile - just 'brittle people'

Males do not cause all of the violence. In 1979 in San Diego, Brenda Spencer reportedly said her motive for the shooting of elementary schoolchildren was that she didn't like Mondays because they were boring.

School violence is not limited to the United States either. Think Bastian Bosse at the Geschwister Scholl School in Germany in 2006.

These examples of school violence, especially the ones in our recent past, might cause one to think we have an epidemic. Nothing could be further from the truth. Our schools still are incredibly safe - much safer than life out on the street. A student has a one-in-1-million chance of dying from violence at school. Nevertheless, even one death is too many.

Who are the people who commit these acts of violence at our schools? Unfortunately, there is no "profile." Threats could come from our students, faculty, staff, parents and outsiders. Literally, anyone is a potential threat.

Research conducted by the FBI, the Secret Service and individuals like Dr. Kris Mohandie generally have come to the conclusion that although several factors might lead to someone acting out violently, a common trait could be that a small percentage of our population is unable to cope with bullying, harassment or rejection, except by acting out violently.

Those people sometimes are referred to as "brittle people." They are like human sponges. Whereas most of us let the perceived injustices of everyday life roll off our backs, the "brittle people" just can't let them go. These episodes collect inside them and fester until they decide they have had enough and then choose to act out violently.

Another factor might be that most school shooters claim to feel they are persecuted and alienated from their peers, family and the world at large. They feel as though they are outsiders, even if on the surface they appear to be socially involved.

So what can we do? If there is no "profile" of people about to act out violently, how can we stop them?

According to researchers like Mohandie, more than 50 percent of people who have acted out violently had planned their attack for more than two weeks. In a study by Calhoun and Weston, "Contemporary Threat Management" (2003), the findings indicate that people don't just "snap." Rather, they move along a "pathway to violence," which could give us opportunities to intervene before the person acts out.

Recognizing a potential problem

What do we look for and what can schools do? First and foremost, pay attention. Often, people on a pathway to violence will provide clues through their words and actions that they are not happy and intend to harm others.

This is called "leakage." Look for it on social websites like Facebook. Investigators have discovered that individuals who intend to act out violently often publicly post their intentions on social websites in the days leading up to their attack. Many acts of violence have been averted by someone seeing a "troubling" post on a friend's website and reporting it to parents or teachers, who then notify law enforcement.

Unfortunately, we also have seen examples where threats to harm or act out violently have gone unreported because a person didn't believe his or her friend was serious or capable of committing such violence.

Other indicators include a person's withdrawal from normal activities; a severe change in physical appearance or personality; disturbing pictures or drawings on notebooks; expressions of hopelessness in class writing assignments; a sudden interest in or the purchase or securing of weapons or explosives; or verbal warnings issued to friends to stay away from school on a particular day.

Where to turn for help

I have been involved for the past several years in training schools around Ohio on the formation of a threat assessment team (TAT). The teams include such individuals as teachers, coaches, mental-health officials and school resource officers, all working together to identify a potential threat, assess the threat and manage the threat.

Having these go-to people identified to receive information on all potential threats at a particular school means that pertinent information is funneled to someone with the training and understanding necessary to handle the information. Schools also should be encouraged to develop innovative ways for students, staff and concerned citizens to report potential threats, anonymously if necessary, to overcome the fear of retribution or being labeled a "snitch."

The best way to prevent school violence is to assume that it could occur at your school and that it could involve someone you know. You know when someone isn't acting normal or if he or she scares you or concerns you. Report it immediately to someone in authority: parents, teachers, coaches, law-enforcement officials, school resource officers or TAT members.

Don't wait until it's too late. You can make a difference. You might save lives, maybe even a friend's.

Author's note: References used for this column include training received and material from the FBI, U.S. Secret Service, Dr. Kris Mohandie and other sources.

Harry Trombitas is a special agent for the FBI.