School Shootings: What Does Science Say?
Virginia Polytechnic Institute and State University in Blacksburg, Va., generally known as Virginia Tech, was the scene of a mass shooting in 2007.
Credit: Melinda Fawver / Shutterstock.com

School shootings and other violence in school settings stoke the deepest fears of parents, teachers and students themselves.

As classes begin again today in Murrysville, Pa. — scene of a mass stabbing last week that left 21 students and a security guard injured — the school community is working to get back to normal. Suspect Alex Hribal, 16, is being charged as an adult with aggravated assault and attempted homicide, USA Today reports.

After a highly emotional event like an act of school violence, it can be difficult to separate fact from speculation. What does science have to say about school violence? [Understanding the 10 Most Destructive Human Behaviors]

Schools are safer today

It may be easy to overlook this fact in the wake of school shootings, but rates of school violence have fallen significantly. According to a 2013 report from the National Center for Education Statistics (NCES), violent deaths among school students ages 5 to 18 and staff in 2010 were lower than at any time since 1992 (the first year NCES kept records).

There's also an overall downward trend in all suicides and homicides in school settings since 1992, according to the NCES report. The 2006-2007 school year — when 63 homicides and 32 suicides occurred in schools — was an exception, partly due to the Virginia Tech massacre, in which 33 people died.

"I know on the heels of any school shooting, there's the perception that violence is on the rise. It's not," Dewey Cornell, a clinical psychologist and education professor at the University of Virginia, told NPR. "In fact, there's been a very steady downward trend for the past 15 years."

Schools, in fact, may be the safest places for students: The Centers for Disease Control and Prevention (CDC) reported in 2013 that less than 2 percent of all youth homicides occur at school — a percentage that has been stable for about a decade.

The reality of school violence

Nonetheless, school violence is a real (though rare) aspect of modern life. During the 2009-2010 school year, 17 homicides occurred at school among students ages 5 to 18. And about 7 percent of teachers reported they had been threatened or physically attacked by a student, according to NCES data.

Among high-school students in grades 9 through 12, a total of 12 percent reported being in a physical fight on school grounds in 2011, according to the CDC, and 5.4 percent reported carrying a gun, knife or other weapon onto school property in the 30 days before the CDC survey.

The same survey revealed that 7.4 percent of high schoolers had been threatened or injured by a weapon on school property within the previous year, and almost 6 percent reported missing school within the previous 30 days because they felt unsafe on, or traveling to or from, school grounds.

A sense of safety, once taken for granted on school grounds, can be easily threatened: A 2010 study from the Journal of Criminal Justice, completed in the wake of the shootings at Virginia Tech in 2007 and at Northern Illinois University in 2008 (where 6 people died and 21 were injured), revealed that college students felt an increase in fear after the media reported mass shootings.

Violence and the media

Indeed, the news media is frequently blamed for distorting and fueling misperceptions of school shootings and violence.

"When you hear a news announcer say, 'In an all-too-familiar story,' or call these incidents 'epidemic,' I think that's where this [false] impression comes from," Cornell told NPR.

"The information available in news reports is not necessarily complete, accurate or balanced," a 2008 FBI report on school shooters said. "News coverage is inherently hasty and often relies on sources who themselves have incomplete or inaccurate information."

Some observers have charged that this media hype creates a "moral panic" — that is, an overblown sense of alarm caused by a perceived threatening trend.

The FBI report also lists some of the false or unverified impressions of school violence that news coverage manufactures. These include the erroneous assumptions that school violence is an epidemic, all school shooters fit a specific type, access to weapons is the most significant factor and violent students exhibit predictably unusual behaviors.

How school violence occurs

Against these mistaken, but widely believed, impressions, researchers have found, after examining dozens of incidents of school violence, that some patterns do emerge.

Most attacks happen during class hours, according to a 2002 analysis of 26 years of school violence data collected from dozens of states by the U.S. Secret Service and Department of Education. Almost all attackers were current students who acted alone, and all of the attackers were male.

The analysis also revealed that a firearm was the weapon of choice among attackers, and almost half of the attackers carried more than one weapon at the time of their attack.

School violence targeted adults — school faculty, staff or administrators — in 54 percent of the attacks, and attackers had some kind of grievance against at least one of their victims in 73 percent of the attacks.

Who are school shooters?

Creating a profile of a perpetrator of school violence is a daunting task, and though a few researchers claim to have found commonalities among school shooters, experts disagree on whether profiling is a productive or reliable endeavor.

A 2009 study published in the journal Aggression and Violent Behavior found that school-aged mass shooters have a few common characteristics and several differences. Some of the attackers, referred to as "traumatized shooters," came from broken homes typified by parental substance abuse and criminal behavior.

Others, referred to as "psychotic shooters," came from intact families with no history of abuse, but were described as having schizophrenia or a related mental illness. And "psychopathic shooters," who were neither abused nor psychotic, showed narcissism, some kind of sadistic behavior and a lack of empathy. [5 Ways to Foster Self-Compassion in Your Child]

Sadism loomed large in another analysis of school massacres: A study of 23 school attacks occurring from 1988 to 2012, published in February in the journal Homicide Studies, found that 43 percent of the perpetrators had also committed acts of animal cruelty, usually against "anthropomorphized" animals like dogs and cats.

But, though anecdotal reports portray animal cruelty as a precursor of human violence (especially acts of mass murder), "studies reveal mixed support for this notion," the authors of that study were careful to add.

Follow Marc Lallanilla on Twitter and Google+. Follow us @livescience, Facebook & Google+. Original article on Live Science.