49 killed - June 12, 2016 - Omar Saddiqui Mateen, 29, opens fire inside Pulse, a gay nightclub, in Orlando. At least 49 people are killed and more than 50 are injured. Police shoot and kill Mateen during an operation to free hostages officials say he was holding at the club.
32 killed - April 16, 2007 - Virginia Tech in Blacksburg, Virginia. A gunman, 23-year-old student Seung-Hui Cho, goes on a shooting spree killing 32 people in two locations and wounding an undetermined number of others on campus. The shooter then commits suicide.
27 killed - December 14, 2012 - Sandy Hook Elementary School - Newtown, Connecticut. Adam Lanza, 20, guns down 20 children, ages six and seven, and six adults, school staff and faculty, before turning the gun on himself. Investigating police later find Nancy Lanza, Adam's mother, dead from a gunshot wound.
23 killed - October 16, 1991 - In Killeen, Texas, 35-year-old George Hennard crashes his pickup truck through the wall of a Luby's Cafeteria. After exiting the truck, Hennard shoots and kills 23 people. He then commits suicide.
21 killed - July 18, 1984 - In San Ysidro, California, 41-year-old James Huberty, armed with a long-barreled Uzi, a pump-action shotgun and a handgun, shoots and kills 21 adults and children at a local McDonald's. A police sharpshooter kills Huberty one hour after the rampage begins.
18 killed - August 1, 1966 - In Austin, Texas, Charles Joseph Whitman, a former US Marine, kills 16 and wounds at least 30 while shooting from a University of Texas tower. Police officers Ramiro Martinez and Houston McCoy shoot and kill Whitman in the tower. Whitman had also killed his mother and wife earlier in the day.
14 killed - December 2, 2015 - Married couple Syed Rizwan Farook and Tashfeen Malik open fire on an employee gathering taking place at Inland Regional Center in San Bernardino, killing 14 people.
14 killed - August 20, 1986 - In Edmond, Oklahoma, part-time mail carrier Patrick Henry Sherrill, armed with three handguns kills 14 postal workers in 10 minutes and then takes his own life with a bullet to the head.
13 killed - November 5, 2009 - Maj. Nidal Malik Hasan kills 13 people and injures 32 at Fort Hood, Texas, during a shooting rampage. He is convicted and sentenced to death.
13 killed - April 3, 2009 - In Binghamton, New York, Jiverly Wong kills 13 people and injures four during a shooting at an immigrant community center. He then kills himself.
13 killed - April 20, 1999 - Columbine High School - Littleton, Colorado. Eighteen-year-old Eric Harris and 17-year-old Dylan Klebold kill 12 fellow students and one teacher before committing suicide in the school library.
13 killed - February 18, 1983 - Three men enter the Wah Mee gambling and social club in Seattle, rob the 14 occupants and then shoot each in the head, killing 13. Two of the men, Kwan Fai Mak and Benjamin Ng, are convicted of murder in August 1983. Both are serving life in prison. The third, Wai-Chiu "Tony" Ng, after years on the run in Canada, is eventually convicted of first-degree robbery and second-degree assault. He is deported to Hong Kong in 2014.
13 killed - September 25, 1982 - In Wilkes-Barre, Pennsylvania, 40-year-old George Banks, a prison guard, kills 13 people including five of his own children. In September 2011, the Pennsylvania Supreme Court overturns his death sentence stating that Banks is mentally incompetent.
13 killed - September 5, 1949 - In Camden, New Jersey, 28-year-old Howard Unruh, a veteran of World War II, shoots and kills 13 people as he walks down Camden's 32nd Street. His weapon of choice is a German-crafted Luger pistol. He is found insane and is committed to a state mental institution. He dies at the age of 88.