From the Document: "The FBI designated 28 shootings in 2019 as active shooter incidents. The 28 incidents resulted in 247 casualties, 97 people killed, and 150 people wounded, excluding the shooters. No community appears immune from these potential incidents; therefore, it is important for every community to develop an Active Shooter Program. The purpose of this guide is to provide emergency services personnel with the basic building blocks for developing an Active Shooter Program with communities. This guide highlights resources and planning considerations, which will enhance emergency services organizations' ability to develop or improve community planning and preparedness for active shooter incidents."
Cybersecurity and Infrastructure Security Agency: https://www.cisa.gov/