How is an area deemed unsafe and needing to be cordoned off?
Would it be the person at the top of the law enforcement agency (police chief or sheriff) who would make the decision that a particular area is unsafe and needs to be cordoned off with police tape, would it be the elected official at the top (mayor, town supervisor, county administrator), or a judge or magistrate?
What I'm imagining is that after the police tape is put up, and personnel is stationed at the tape to explain to people, if needed, that anyone crossing the tape will be subject to arrest.