They're doing it de facto, because the regional police are refusing to support them or being ordered to withhold support from them.

In a sane world, the crazies would be stopped from interfering, or from putting themselves in harms' way, by the local constabulary--PD, Sheriff's, etc--and the Feds wouldn't have their butts hanging in the breeze to deal with the looky-loos and the kamikarenkazes and angry cat physique simps.

But this is not a sane world at the moment. Politicians are letting their cities go hot to try and blame it on exactly the only people even talking about making things better.