In 1999 after the public outcry over police response to the Columbine High School attack, law enforcement across the nation began developing new strategies for response to such. Typical to law enforcement process (and this isn’t criticism, just reality), the new response protocols were developed to maximize the strengths of law enforcement responders while minimizing risk as much as was realistic given the nature of the call being serviced. What’s that mean?
It means that the “four man diamond” became a fairly standard response protocol. Agencies coast to coast began adopting and teaching this response tactic. The first four officers to arrive on the scene of a shooting teamed up and made entry; moved to the sound of the shooter and neutralized same. “Neutralized” could mean arrest OR it could mean “ventilate a lot.” The obvious most important goal was to stop the shooter from hurting anyone else as quickly as possible.
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The remainder of this article is part of the book "Active Killers and the Crimes They Perpetrated," available in print or ebook via Amazon.

Joshua Borelli
Joshua Borelli has been studying active shooter and mass attack events over the course of the past several years, commensurate with receiving training on response and recovery to natural disasters and civil disturbances. Joshua started to outline this series of articles in an attempt to identify commonalities and logistical needs patterns for response.