What should you do first when a fire alarm sounds?

When a fire alarm sounds, the immediate priority is to evacuate the building. This is essential for safety, as fire alarms are designed to alert occupants to a potential emergency, often indicating a real threat to life and property. Evacuating allows all individuals to leave the premises quickly and safely in compliance with established fire safety procedures.

Investigation of the alarm's source, while important, should only occur if it is safe to do so or after ensuring that everyone has evacuated. Calling 911 is a critical action but should happen once you are in a safe location outside the building. Disabling the alarm is not advisable, as it could prevent others from being alerted to the danger and compromise their safety. Therefore, immediate evacuation is the most vital response to ensure everyone's well-being in the event of a fire alarm activation.