Federal Emergency Management Agency
is to coordinate the response to a disaster which has occurred in the United States and which overwhelms the resources of local and state authorities.  The governor of the state in which the disaster occurred must declare a state of emergency and formally request from the President that FEMA and the federal government respond to the disaster. The only exception is when an emergency or disaster occurs on federal property or to a federal asset, for example, the Alfred P. Murrah Federal Building in Oklahoma City, Oklahoma, in the 1995 bombing, or the Space Shuttle Columbia in the 2003 return-flight disaster.