The present Reverse 911 Alarm System implements a central alarm distribution site that is capable of generating an alarm indication to warn individuals of a hazard and propagating the alarm indication to selected individuals via their wireless subscriber devices by the use of wireless multicasting in the existing cellular communication network and/or wireless-based Local Area Networks which are operational in the coverage area of the hazard. The central alarm distribution site dynamically selects the wireless coverage area to encompass the present extent of the hazard and can also provide advanced warning to individuals located in an area that extends beyond the present hazard extent area. The present Reverse 911 Alarm System thereby integrates the operation of the wireless communication network with the 911 and Reverse 911 services to provide efficient and comprehensive distribution of alarm indications to the individuals who are impacted by an emergency situation.