Deadly mass shooting incidents are taking place more frequently in the U.S. with the last seven years witnessing more than twice the number of such incidents reported prior to that time period, according to a new FBI study, released Wednesday. The study included 160 “active shooting incidents” that occurred between 2000 and 2013 throughout the nation.

According to FBI, the study is expected to provide first responders with data that can help them better prepare for, and respond to, such incidents in more effective ways. The agency also expects the findings of the study, which began in early 2014, to benefit anyone who could potentially be in a similar situation.

The study “demonstrates the need not only for enhanced preparation on the part of law enforcement and other first responders, but also for civilians to be engaged in discussions and training on decisions they’d have to make in an active shooter situation,” Katherine Schweit, who heads the FBI’s Active Shooter Initiative, said in a statement.

According to the study, which was conducted with assistance from Texas State University’s Advanced Law Enforcement Rapid Response Training Center, an average of 16.4 active-shooter incidents a year were reported between 2006 and 2013, which was up from an average of 6.4 incidents a year between 2000 and 2006. In all these incidents, 486 people were killed and 557 were wounded, excluding the shooters.

Mass_shooting_FBI Mass shooting incidents are taking place more frequently in the U.S., according to FBI. Photo: FBI

In 21 of the 160 incidents, nine officers were killed and 28 were wounded, while 90 shootings ended with the shooter committing suicide or fleeing. In 21 incidents, unarmed citizens successfully restrained the shooter, according to the study, which did not include gang- or drug-related killings.

Mass_shooting_FBI2 In 21 of the 160 incidents nine officers were killed and 28 were wounded, FBI study said. Photo: FBI

Most of the shootings -- 45.6 percent or 73 incidents -- occurred in commercial locations, followed by 39 incidents (24.3 percent) in educational settings, such as schools or colleges, according to the report. The remaining incidents took place in other locations, including open spaces, military and other government properties, residential properties, houses of worship and health care facilities.

In addition, many of the shootings lasted for a matter of minutes. In 23 shootings, for example, the violence ended in less than two minutes, while about two-thirds of them got over before police arrived at the scene, the Wall Street Journal reported.

The 160 incidents studied by the FBI included the shootings at Virginia Tech university in April 2007; the U.S. Holocaust Memorial Museum in June 2009; Fort Hood in November 2009; the Aurora (Colorado) Cinemark Century 16 movie theater in July 2012; the Sikh Temple of Wisconsin in August 2012; Sandy Hook Elementary School in December 2012; and the Washington Navy Yard in September 2013.