The Federal Bureau of Investigation (FBI) has just released “A Study of Active Shooter Incidents in the United States Between 2000 and 2013.” The agreed-upon definition of an active shooter by U.S. government agencies—including the White House, U.S. Department of Justice/FBI, U.S. Department of Education, and U.S. Department of Homeland Security/Federal Emergency Management Agency—is “an individual actively engaged in killing or attempting to kill people in a confined and populated area.” According to the study:

• An average of 11.4 incidents occurred annually.
• An average of 6.4 incidents occurred in the first 7 yrs studied, and an average of 16.4 occurred in the last 7 yrs.
• 70.0% of the incidents occurred in either a commerce/business or educational environment
• Shootings occurred in 40 of 50 states and the District of Columbia.
• 60.0% of the incidents ended before police arrived.

Read more here.