A wearable apparatus for personal safety has a scene monitor for sensing an ambient environment, and a main controller for processing the scene data. An emergency condition adverse to a user is detected by processing captured images of the ambient environment to determine whether a violent movement signifying the user facing an attack or accident has occurred. Motion data measured by a motion sensor in the apparatus can be used, alone or with captured images, to assist this determination. Upon detection of the emergency condition, the apparatus automatically sends scene data most-recently obtained before the emergency condition occurs to a remote server for securely storing these scene data for future uses even if the apparatus is subsequently damaged by, e. g., an attacker. The sending of scene data is automatic without a need for the user to initiate. Microphone, hazardous-gas sensor, etc. may also be used in sensing the ambient environment.