You should delete your post. You have no reason to cite this. You weren't there, you weren't under fire, you weren't responsible for innocent lives and unless you are claiming someone was grossly incompetent, instead of simply making a mistake in the heat of the moment, there is no reason for you to get involved in this.
The PD was grossly incompetent at Columbine. Why else would it take them 3 hours to finish clearing the building? By the end, there were 600+ officers on site.
Contrast the performance of the Santa Barbara County Sheriffs Department January 30, 2006, when a woman entered a postal processing center and killed 7. The SB Sheriffs entered the building rapidly and did not wait for hours safely behind barricades.