The 2001 anthrax attacks were a series of bioterrorism incidents that occurred in the United States shortly after the September 11 attacks. Letters containing anthrax spores were mailed to several news media offices and two Democratic Senators, Tom Daschle and Patrick Leahy, resulting in five deaths and 17 infections. The attacks caused widespread fear and led to significant public health responses, including the testing of mail and buildings for anthrax contamination. Investigations by the FBI and other agencies focused on identifying the source of the anthrax, which was eventually traced to a government laboratory.