A system is configured to assist occupants of a building in response to an active shooter situation. A plurality of sensor units are arranged in the building to detect a gunshot and generate a signal indicative of the gunshot. A processing system determines an approximate location of the gunshot based on the signal and determines safe areas and unsafe areas in the building based on the approximate location of the gunshot. A plurality of output devices are in the building and in communication with the processing system. The output devices indicate an evacuation path within the safe areas with a first graphic and indicate the unsafe areas with a second graphic that is different from the first graphic. An indicator is arranged in a room and generates a lock down indication to notify occupants to stay in the room in response to the processing system receiving the signal.