"In 2013, the president signed into law the Investigative Assistance for Violent Crimes Act of 2012, which granted the attorney general the authority to assist in the investigation of 'violent acts and shootings occurring in a place of public use' and in the investigation of 'mass killings and attempted mass killings at the request of an appropriate law enforcement official of a state or political subdivision.' To provide further clarity on these threats, the Federal Bureau of Investigation (FBI) in 2014 initiated a study of 'active shooter' incidents . The goal of the FBI study is to provide federal, state, and local law enforcement with data so they can better understand how to prevent, prepare for, respond to, and recover from these incidents."
2014 Texas State University and Federal Bureau of Investigation, U.S. Department of Justice, Washington D.C.
Federal Bureau of Investigation: http://www.fbi.gov/