In that hypothetical scenario, the police would be responding to an attack (staged or otherwise). Later, the immediate security measures put in place in response to the attack simply wouldn't be wound down over time, maybe because of additional attacks against notable weak points of the existing security measures. Also, cell phone and Internet service would be shut down (ostensibly to prevent attackers from triggering remote detonators, which obviously could never have timers or dead man's switches), thus preventing the on-duty emergency security police from getting news from an outside source.

It's an interesting hypothetical scenario which exploits the good intentions of the police and military to do evil.