Catastrophic events can range from natural disasters such as Hurricane Maria which devastated Puerto Rico on September 20, 2017[1] to mass casualty terrorist attacks such as when the World Trade Center was destroyed on September 11, 2001. Hydrometeorological catastrophes such as hurricanes, tornadoes, and floods are predictable. On the other hand, geologic disasters such as earthquakes are not. Many natural disasters affect the entire infrastructure from buildings, roads, electricity, and communication. While natural disasters can affect all, they disproportionately affect the poor and vulnerable. Terrorist attacks will usually affect urban areas as they have an intentional goal to cause as many victims as possible. Complex humanitarian emergencies result in deaths from violence as well as disease. A multi-casualty incident (MCI) is an event in which the resources available (rescue personnel, healthcare providers, facilities, and equipment) are insufficient to deal with the incident. In a disaster, not only are there not enough resources, but there is a complete breakdown in communication and the ability to deliver these resources. The local rescue workers and health care personnel, may themselves become the victims or be unable to arrive at work. The local health care facilities may be damaged or destroyed.