When the people inside go to sleep at night.
When faced with overwhelming force, don't be a dumbass and try to take it head on. The tactical answer is to know where they are and counter where they are not.
Cops wouldn't stand a chance against popular civil resistance. Their families would be dead in no time, their houses burned, their food poisoned. They wouldn't be able to take a step without someone taking a potshot at them. Cops, not being cohesive and battle-tested military units, will fall into disarray quickly as morale drops under these conditions, many will desert, and many others will defect and join the resistance.