Active Shooter ≠ Hostage Crisis
Even in a hostage situation, once they start shooting hostages, you stop trying to negotiate and start breaching.
Professional LE negotiators are a first resort. Sometimes they succeed, other times they fail. Once failed, it's time to breach.
Precisely.
Wounded, innocent children might bleed out quickly. Attempting to "negotiate" (foolish on the face of it) works directly against their survival.
Not enough has been made on the critical point, that wounded, innocent children might bleed out too quickly for anything but a rapid response by motivated, competent law enforcement.