This is exactly what the terrorists want. An undisciplined mob will end up shooting themselves before hitting a terrorist. I won't even dream of the cause and effect of such a scenario.
There would be no way the islamofascist terrorists inside would make it out of there alive. In fact, the citizens would so outnumber the police, and in their anger, were the terrorists to be apprehended by police, they would be seized forceably on the spot from the police, and probably lynched right there, citizens firing round after round into their hanging bodies. That is what would happen in Red State, Fly Over America.