A system, method, and apparatus to alert individuals at a site to an incident, such as an active shooter. The site may involve a school campus or other site in which large numbers of people assemble. Receiver/transmitter assemblies are deployed in discrete occupation units of the site and communicate with a central server and are mapped to a specific location on the site. The receiver/transmitter assemblies communicate a voice alert to the server where it is analyzed to provide a localization of the incident and a mapping within the site. A notification provides information based on a role of the recipient where a first responder role receives information to contain the incident. Any building occupant can initiate an alert to others. Occupants unaware of the unfolding of an active shooter event may receive instructions to shelter in place or evacuate the site. Visual or audible egress routing may be provided.