From the Document: "On Sunday, June 12, 2016, approximately 50 people were killed (including the alleged assailant), and 53 more were injured in an attack on a nightclub in Orlando, FL, that catered to the lesbian, gay, bi-sexual, and transgender (LGBT) community. The alleged assailant was armed with a 5.56 caliber Sig Sauer rifle and a 9mm Glock semiautomatic. The Bureau of Alcohol Tobacco, Firearms, and Explosives (ATF) has reported that these weapons were legally purchased in Florida. During the assault on the nightclub, the alleged assailant reportedly called 911 to pledge allegiance to ISIS [Islamic State of Syria and Iraq]. The assailant was killed by police after a standoff that lasted approximately three hours. This incident is the worst mass shooting in U.S. history to date. CRS [Congressional Research Service] has several different products on issues relevant to the mass shooting incident in Florida. These issues include mass murder with firearms, firearms regulation, domestic terrorism, and hate crime. Below are key products on these issues. Congressional clients may contact the authors of the individual reports for additional information on the issues."
CRS Report for Congress, R44520
Congressional Research Service: https://crsreports.congress.gov/