A proximity based ad-hoc messaging, alerting, and tracking system can be employed to quickly and efficiently propagate alerts when a child or other individual becomes lost. Various types of alerts can be provided to facilitate locating a lost individual even in scenarios where a network connection or GPS is not available. The system can also be employed to track the presence of an individual after traveling in a vehicle to enable detecting when the individual has been separated from all guardians such as would be the case when the individual is left in the vehicle.