Critical and emergency incidents often lead to asset, infrastructure and human loss, all major concerns for companies, organizations and governments. Early prediction, emergency management plans and immediate dissemination of information can mitigate such events from occurring. To this end, early warning systems have been deployed. Early warning systems comprise of sensors, event detection and decision subsystems that work together to forecast the occurrence of possible incidents. These forecasts are then processed by a mass notification system for the dissemination of public alert guidelines and coordinated emergency group actions. While these systems reduce risks and enable authorities’ coordination, their deployment often fails to offer timely alerts specifically in case of incidents affecting a massive number of participants. This study presents existing notification systems, their minimum requirements and technical challenges for large scale deployments. Furthermore it proposes a high level architecture and required features for a mass notification system which focuses on public safety and protection of life and property on a large scale.