Most preK-12 school districts in the United States dedicate significant resources to safeguard against active shooters, e.g., school hardening, community planning, identification of suspicious behavior, crisis training for law enforcement, and training exercises for students, teachers, and all school personnel. However, when such an active-shooting event is in progress, only vague guidance is available to students and school personnel in the form of directives such as the "run-hide-fight" protocol. The Active Shooter Tracking and Evacuation Routing for Survival (ASTERS) project will complement these efforts by tracking a shooter in real time across multiple cameras and microphones, calculate the optimum evacuation path to safety for each student, teacher, and staff member, and communicate this information through a mobile app interface that is co-created in partnership with a connected community of students, parents, educators and administrators as well as school resource officers and school safety officers. ASTERS will incorporate multi-modal sensing, machine learning and signal processing techniques to accurately localize a gunman and weapons while preserving privacy of school community members. It will also use new computer vision and high-performance computing solutions to estimate crowd density and movement of people, and novel optimization and real-time simulation algorithms to predict ideal evacuation routes based on the building layout and predicted movement of the shooter. ASTERS will collaborate with schools to develop an annotated, multi-modal active shooter data set using a combination of digital simulation data and real-life practice drills. The research team will also partner with first-responders to ensure that ASTERS aligns with their needs. <br/><br/>Providing customized and actionable commands to each group of civilians through a mobile app will potentially vastly improve chances of safe evacuation. Messages will provide clear actionable information and suggestions, such as "Shooter is leaving the cafeteria heading to the gym. Your best exit is out the Main Entrance", rather than leave it up to individuals' panicked judgement. Moreover, ASTERS will enable automated and instantaneous reporting of location and physical attributes of shooter and type of weapons being used, to a 911 call center. This will provide responding patrol officers with critical strategic information for planning a tactical offensive and alleviate, if not overcome, the dependence on unreliable eye-witness accounts. Data from previous mass shootings demonstrate the important of providing people accurate information and guidance about evacuation. The ASTERS project will enable the realization of smart safety systems that integrate sensors, communication, algorithms, and human factors research to provide life-saving information to vulnerable people.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.