Final answer:
The first step is to alert everyone and begin evacuation, pull the fire alarm, call 911, and notify your supervisor.
Step-by-step explanation:
The first step to take when encountering a fire that you think is too large to control by yourself in a building you are patrolling is to alert everyone in the area of the danger and begin assisting evacuation to a safe location. This includes closing all doors behind you. It is important to pull the fire alarm to notify others of the emergency. Call 911 immediately to report the fire and provide them with the necessary information. Additionally, you should notify your supervisor about the situation.
By following these steps, you can help ensure the safety of everyone in the building and provide the necessary information to the authorities and emergency response teams.