Pinnacle Charter School high school students practice evacuating during training for an active shooter situation in a school in Thornton, Colorado, U.S. August 28, 2019.

Chad Miller, CEO of Pinnacle Charter School (L) is reflected in a window watching Joe Deedon, president of TAC*ONE, showing Pinnacle Charter School high school students an evacuation procedure during TAC*ONE training for an active shooter situation in a school in Thornton, Colorado, U.S. August 28, 2019.

Pinnacle Charter School high school student Gregory Younce practices self-defense with trainer Alexis Halkovic during training for an active shooter situation in a school in Thornton, Colorado, U.S. August 28, 2019.

A girl reacts (L) as Joe Emery, TAC*ONE trainer and former Las Vegas police department sergeant, tells 3rd grade students about a shooter's intent at Pinnacle Charter School during TAC*ONE training for an active shooter situation in a school in Thornton, Colorado, U.S. August 29, 2019.

Joe Deedon, president of TAC*ONE, shows a Pinnacle Charter School high school student an evacuation procedure during TAC*ONE training for an active shooter situation in a school in Thornton, Colorado, U.S. August 28, 2019. Picture taken August 28, 2019.

Joe Deedon, president of TAC*ONE, shows a Pinnacle Charter School high school student an evacuation procedure during TAC*ONE training for an active shooter situation in a school in Thornton, Colorado, U.S. August 28, 2019. Picture taken August 28, 2019.

Joe Deedon, president of TAC*ONE, shows Pinnacle Charter School high school students an evacuation procedure during TAC*ONE training for an active shooter situation in a school in Thornton, Colorado, U.S. August 28, 2019.

Pinnacle Charter School high school student Zoe Marie Musser (R) practices taking down a shooter during training for an active shooter situation in a school in Thornton, Colorado, U.S. August 28, 2019.

Fifth grade student Alondra Gomez shows how to tie a door shut in a exercise at Pinnacle Charter School during TAC*ONE training for an active shooter situation in a school in Thornton, Colorado, U.S. August 29, 2019.

A door blockading device is seen across a classroom door at Pinnacle Charter School during TAC*ONE training for an active shooter situation in a school in Thornton, Colorado, U.S. August 29, 2019.

Kindergarten students at Pinnacle Charter School listen to an instructor during TAC*ONE training for an active shooter situation in a school in Thornton, Colorado, U.S. August 29, 2019.

Joe Deedon, president of TAC*ONE, demonstrates the sound of a pistol slide being racked to hundreds of Pinnacle Charter School high school students during TAC*ONE training for an active shooter situation in a school in Thornton, Colorado, U.S. August 28, 2019.

Pinnacle Charter School high school students practice self-defense moves during training for an active shooter situation in a school in Thornton, Colorado, U.S. August 28, 2019. Picture taken August 28, 2019.

Joe Emery, TAC*ONE trainer and former Las Vegas police department sergeant, speaks to kindergarten students at Pinnacle Charter School during TAC*ONE training for an active shooter situation in a school in Thornton, Colorado, U.S. August 29, 2019.

Second grade students at Pinnacle Charter School listen to an instructor during TAC*ONE training for an active shooter situation in a school in Thornton, Colorado, U.S. August 29, 2019.

A Pinnacle Charter School high school student practices taking down a shooter during training for an active shooter situation in a school in Thornton, Colorado, U.S. August 28, 2019. Picture taken August 28, 2019.

Pinnacle Charter School high school students practice evacuating during training for an active shooter situation in a school in Thornton, Colorado, U.S. August 28, 2019.

Kindergarten students at Pinnacle Charter School are seen in a mirror listening to an instructor during TAC*ONE training for an active shooter situation in a school in Thornton, Colorado, U.S. August 29, 2019.

First grade students at Pinnacle Charter School listen to an instructor during TAC*ONE training for an active shooter situation in a school in Thornton, Colorado, U.S. August 29, 2019.

Pinnacle Charter School high school student Christopher Eichman practices taking down a shooter during training for an active shooter situation in a school in Thornton, Colorado, U.S. August 28, 2019.

Joe Emery, TAC*ONE trainer and former Las Vegas police department sergeant, speaks to kindergarten students, some seen in mirror at right, at Pinnacle Charter School during TAC*ONE training for an active shooter situation in a school in Thornton, Colorado, U.S. August 29, 2019.

Pinnacle Charter School high school students practice CPR on a doll, simulating the pressure needed for CPR, during training for an active shooter situation in a school in Thornton, Colorado, U.S. August 28, 2019. First aid and CPR were part of the training.

Joe Emery, TAC*ONE trainer and former Las Vegas police department sergeant, speaks to kindergarten students at Pinnacle Charter School during TAC*ONE training for an active shooter situation in a school in Thornton, Colorado, U.S. August 29, 2019.

Joe Deedon, president of TAC*ONE, speaks to hundreds of Pinnacle Charter School high school students during TAC*ONE training for an active shooter situation in a school in Thornton, Colorado, U.S. August 28, 2019.

Joe Emery, TAC*ONE trainer and former Las Vegas police department sergeant, leads kindergarten students in evacuation training at Pinnacle Charter School during TAC*ONE training for an active shooter situation in a school in Thornton, Colorado, U.S. August 29, 2019.

Joe Deedon, president of TAC*ONE, speaks to hundreds of Pinnacle Charter School high school students during TAC*ONE training for an active shooter situation in a school in Thornton, Colorado, U.S. August 28, 2019.