Emergency evacuation is the urgent immediate egress or escape of people away from an area that contains an imminent threat, an on-going threat or a hazard to lives or property.
A hazard is an agent which has the potential to cause harm to a vulnerable target.
Emergency Evacuation Procedures by ACSASafety
Examples range from the small scale evacuation of a building due to a storm or fire to the large scale evacuation of a city because of a flood, bombardment or approaching weather system.
A storm is any disturbed state of an environment or astronomical body's atmosphere especially affecting its surface, and strongly implying severe weather.
A low-pressure area, low, or depression is a region where the topographic map is atmospheric pressure is lower than that of surrounding locations.
Fire is the rapid oxidation of a material in the exothermic chemical process of combustion, releasing heat, light, and various reaction products.
Emergency Evacuation: What Every Employee Should Know DVD by National Fire Protection Association
In situations involving hazardous materials or possible contamination, evacuees may be decontaminated prior to being transported out of the contaminated area.
Contamination is the presence of an unwanted constituent, contaminant or impurity in a material, physical body, natural environment, workplace, etc.