Last year saw the most active shooter situations since the FBI first began keeping track.
An agency report says there were 30 situations in 2017 and that 138 people were killed in those shootings.
The FBI defines an active shooter situation as one in which at least one individual is "actively engaged in killing or attempting to kill people in a populated area." The bureau doesn't include gang violence. It began keeping track of active shooter situations in 2000.
A former FBI agent told USA Today that the high number of active shooter events may be due to several factors, including accessibility to guns and copycats.