Thor Eells, executive director of the National Tactical Officers Association (NTAO), said the commander’s determination was “100% flawed.” A barricade calls for officers to slow down their response, analyze whether the subject is alone and negotiate, he said.

“If you’re in a classroom with innocent victims and I know that shots have been fired, I need to engage you. Even if you stopped firing, I’m going to make entry into the room so we can begin to administer life-saving aid to any potential victims,” Eells said…

Eells pointed to a 2013 shooting at a Colorado high school that shows how a rapid response by police can lead to vastly different results. The shooting transpired within two minutes, during which a male high school student ignited a Molotov cocktail and fired his pump-action shotgun in the school, fatally shooting a 17-year-old girl.

But the attack might have resulted in many more casualties had it not been for the quick response of a deputy sheriff who was working as a school resource officer at the school, CNN previously reported. Upon learning of the threat, the deputy ran to the shooter, identified himself as a county deputy sheriff and told people to get down. While he was containing the scene, the shooter took his own life.