An unauthorized radio transmission was broadcast on a frequency used by the Chicago Police Department, according to the Chicago Tribune.
Office of Emergency Management and Communications Spokesperson Melissa Stratton said that the "rogue radio transmission" occurred on Wednesday evening.
The unauthorized user reportedly was rambling on in what one person told the Tribune was "a very scary, intense, angry story."
A dispatcher reportedly told officers, "A little bit of an officer safety hazard on the zone at the moment, so anybody with any emergency please switch over to a citywide."
The investigation into the unauthorized transmission remains ongoing.