What typically prompts all occupants to evacuate the building?

Fire alarms are designed to alert building occupants to potential emergencies, particularly fires. When a fire alarm is activated, it produces a loud sound and sometimes flashes lights, which are intended to quickly capture the attention of everyone inside the building. This audible alert serves as a critical signal for occupants to evacuate immediately and take necessary safety measures.

The function of fire alarms is specifically geared towards fire safety, as their activation reflects a direct threat to life and property. Therefore, they are the most reliable prompt for an evacuation when compared to other methods of notification. While visible signs of smoke and directives from emergency personnel can also lead to evacuations, they are not as systematic or universally heard as a fire alarm. Additionally, security announcements may not carry the same urgency or immediate imperative to leave the premises. Thus, fire alarms stand out as the primary trigger for evacuation in emergency situations.