There have been many active shooter incidents in the United States since Columbine, and police agencies continue to modify their policies and training to reflect the lessons that are learned from each new tragedy. This report summarizes the state of the field as of 2014. The Police Executive Research Forum conducted research on these issues and held a one-day Summit in Washington, D.C., in which an overflow crowd of more than 225 police chiefs and other officials discussed the changes that have occurred, and where they are going from here
