The shooting spree at Fort Hood, Texas on November 5, 2009, by Maj. Nidal Hassan that killed thirteen soldiers and civilians and injured more than a dozen other soldiers and civilians has led to claims against the government totaling some $750 million.  The family members and individuals harmed by the shootings claim that the government was willfully negligent in ignoring repeated and obvious signs that Maj. Nissan posed a grave risk of horrendous violence. 

Source: New York Times

The claims against the government appear to be brought under the Federal Tort Claims Act. The Federal Tort Claims Act allows individuals and families to bring suit in certain situations for injuries caused by the negligence of government employees and agents.