© Reuters/Neal HambergSWAT officers patrol the Copley Square area after explosions near the finish line of the Boston Marathon in Boston, Massachusetts April 15, 2013.
The study concentrated on 160 "active shooter incidents" between 2000 and 2013. Such incidents are defined as cases in which an attacking gunman shoots or attempts to shoot people in a populated area. The FBI excluded shootings that were gang- or drug-related.
The report found that during the first seven years involved in the study, an average of 6.4 "active shooter incidents" occurred each year. That average increased to 16.4 per year in the final seven years studied.
The largest portion of such incidents - 73 total, or 45.6 percent of all examined attacks - took place at a business, or "commercial environment," the FBI found. Just over 24 percent, or 39 incidents, occurred at schools. The rest of the attacks studied happened at other locations, including military and other government properties, residential properties, open spaces, places of worship, and health care outlets.
© Reuters/Eduardo MunozStreet artist Mark Panzarino, 41, prepares a memorial as he writes the names of the Sandy Hook Elementary School victims during the six-month anniversary of the massacre, at Union Square in New York, June 14, 2013.
All but six of the 160 incidents involved male attackers. Only during two incidents were there more than one gunman involved.
Just over half of the attacks, or 90 shootings, ended "on the shooter's initiative," such as suicide or fleeing the scene, according to the FBI. Twenty-one incidents ended once unarmed citizens immobilized the shooter.
In 21 of the 45 attacks where law enforcement engaged the shooter to end the incident, the FBI found that nine officers were killed and 28 were wounded.
The report includes infamous attacks in this time period, such as those occurring at Virginia Tech, Sandy Hook Elementary School, the US Holocaust Memorial Museum, Fort Hood, the Aurora (Colorado) Cinemark Century 16 movie theater, the Sikh Temple of Wisconsin, and the Washington Navy Yard.
The FBI's stated goal with the report - conducted with assistance from Texas State University's Advanced Law Enforcement Rapid Response Training Center - is "to provide our law enforcement partners - normally the first responders on the scene of these dangerous and fast-moving events - with data that will help them to better prepare for and respond to these incidents, saving more lives and keeping themselves safer in the process," according to the FBI.
© Reuters/John GressSikhs and members of the community attend a vigil in Oak Creek, Wisconsin, August 7, 2012.
"The copycat phenomenon is real," said Andre Simons of the FBI's Behavioral Analysis Unit, according to NBC News. "As more and more notable and tragic events occur, we think we're seeing more compromised, marginalized individuals who are seeking inspiration from those past attacks."
What role issues such as economic despair, lack of mental health care, or life in an alienating society that rewards cruelty were not included in the report by the FBI, the nation's largest law enforcement body.
Reported that no one died in Newtown, CT in 2012. That would have included the Sandy Hook school. For this report, are these "casualty" numbers imaginary from staged events?