If you experience an active shooter incident, you should prioritize evacuating the building. Leaving the building is the surest way to safety. When others insist on staying, you should encourage them to leave with you. However, their choice to stay should not slow you down.
As you're evacuating, do not try to move injured people. Doing so may only put you in danger. Leave behind your belongings. At the end of the day, your life is the most important thing.
If you can safely exit the building, prevent others from entering the area. Call 9-1-1 as soon as you are safe.