When necessary, evacuation is the first choice of action; however, sometimes conditions for a safe evacuation do not exist, and the public is asked to "shelter-in-place".
What is Shelter-in-Place? Shelter-in-Place means people should seek shelter inside a building and remain inside until the danger passes. Sheltering-in-place is used when evacuating the public would cause greater risk the staying where they are, or when an evacuation cannot be performed. Follow the instructions provided by authorities, but normally shelter-in-place means people stay inside and close all doors and windows and remember to shut off all ventilating, heating and cooling systems.