This means that regardless to how fast/well armed the first response is, it will NOT engage the potential threat directly unless forced to anyway.. That is why incidents like columbine go on for so long.. Who is the subject in question? What are they armed with? How many? Do they have hostages? Will we further endanger lives by moving in too fast without correct intel? Did they set traps? Are there IEDs present?
Columbine could be considered the first of its kind, where the police took it as a hostage type situation. Alot has changed since then in police tactics such. http://en.wikipedia....apid_Deployment Even my local county police has a emergency plan like this, if there was something happening at a school, the first two or three patrol cars would divide up into like two teams of two and make immediate entry. It doesn't always prevent the damage from occuring, but it defiantly stops sooner. It is also one reason why many places provide assault rifles to officers in patrol cars. In these cases, SWAT or ESU gets there after the fact.