Written by members of the Advanced Law Enforcement Rapid Response Training (ALERRT) Center at Texas State University, this book is the culmination of more than a decade's worth of training and research into active shooter events. Empowering law enforcement professionals by leveraging the essential knowledge and experience of those who have gone before us, the book also offers insight into the training methodologies and strategies used to prepare our nation's first responders to address the active shooter threat. In addition, the authors discuss the clear and present threat of terrorist organizations using these mass shooter tactics on American soil.