"The Stafford Act has been used to provide assistance in response to terrorist attacks in the past […] Nevertheless, the tactics used in recent incidents such as the 2015 San Bernardino, CA, and the 2016 Orlando, FL, mass shootings, and the 2016 Ohio State University vehicular and knife attack, have brought to light two main challenges that might prevent certain types of terrorist incidents from receiving the wider assistance provided under a major disaster declaration:  the major disaster definition lists specific incident types that are eligible for federal assistance. Past terrorist incidents were considered major disasters, in part, because they resulted in fires and explosions. Incidents without a fire or an explosion may not meet the definition of a major disaster; and  the Federal Emergency Management Agency's (FEMA) recommendation to the President to issue a major disaster declaration is mainly based on damage amounts to public infrastructure compared to the state's population. Terrorist incidents with a large loss of life but limited damage to public infrastructure may not meet this criterion [...] This report provides an overview of emergency and major disaster declarations and explains how they might be used in the aftermath of a terrorist incident that does not involve a fire or an explosion, such as high casualty mass shootings or chemical gas attacks. This report also provides an overview of Stafford Act assistance provided for past terrorist incidents."
CRS Report for Congress, R44801
Federation of American Scientists: http://www.fas.org/sgp/crs/index.html