Oct. 2, 2017: Thousands of country music fans became witnesses or victims of the deadliest mass shooting in modern US history when a gunman unleashed "hundreds" of bullets into the Las Vegas Strip crowd. At least 50 people were killed.
Forty-nine people were killed in a June 2016 shooting at Pulse, a gay nightclub in Orlando, Florida.
Dec. 2, 2015: Authorities say Syed Rizwan Farook, 28, "angrily" left a holiday party at the Inland Regional Center in San Bernardino, California. Farook's wife, Tashfeen Malik, drove him back to the center and the couple re-entered the facility firing weapons and ended up killing 14 people and injuring 17 others. The couple tried to escape in a SUV until authorities caught up with them about 2 miles from Inland Regional. Farook and Malik were killed in a shootout with police that involved 21 officers, authorities said.
April 2, 2014: Spc. Ivan Lopez killed three people and wounded 16 others at the Fort Hood military post in Texas before fatally shooting himself, authorities say.
Sept. 16, 2013: Authorities say military contractor Aaron Alexis gunned down 12 people and wounded eight others at the Washington Navy Yard before he was killed.
Dec. 14, 2012: Gunman Adam Lanza massacred 20 first-graders and six staff members at Sandy Hook Elementary School in Newtown, Conn. He shot his mother to death before going to the school, and killed himself as authorities arrived.
Aug. 5, 2012: Six people were killed and four wounded when Wade Michael Page, 40, opened fire with a Springfield 9mm semi-automatic handgun at a Sikh temple in Oak Creek, Wis. According to the FBI, Page died from a self-inflicted gunshot wound to the head after he was shot in the stomach by a responding officer.
July 20, 2012: A gunman opened fire inside an Aurora, Colorado, movie theater during a midnight showing of the Batman sequel "The Dark Knight Rises," killing 12 and wounding 70 others. The sole suspect is James Eagan Holmes, who was arrested outside the cinema minutes later. In the summer of 2015, Holmes was convicted on 24 counts of murder and 140 counts of attempted murder and sentenced to 12 consecutive life sentences plus 3,318 years without parole.
Jan. 8, 2011: Jared Lee Loughner killed six and wounded 13, including then-Rep. Gabrielle Giffords, outside a grocery store in Tucson, Ariz. Loughner pleaded guilty in 2012 and was sentenced to life in prison without the possibility of parole.
Nov. 5, 2009: Maj. Nidal Malik Hasan, a 39-year-old U.S. Army psychiatrist of Palestinian descent, killed 13 and wounded 29 at Fort Hood, located just outside Killeen, Texas, in the deadliest mass shooting at a United States military installation. Hasan was shot and taken into custody by responding officers and is now paralyzed from the waist down. He was eventually convicted on 13 counts of premeditated murder and 32 counts of attempted murder and sentenced to death. Hasan remains imprisoned at the United States Disciplinary Barracks at Fort Leavenworth in Kansas awaiting execution while his case is reviewed by appellate courts.
April 3, 2009: Vietnamese immigrant Jiverly Wong, 41, opened fire in an immigrant community center in Binghamton, New York, killing 13 people and wounding another four before taking his own life.
March 30, 2009: A gunman shot eight people to death and wounded several others at a nursing home in North Carolina. Most of those killed were elderly nursing home patients.
March 29, 2009: A gunman killed five family members, including his two children, and wounded his wife at a townhome in Santa Clara, Calif., before killing himself.
Sept. 2, 2008: Isaac Zamora, 28, was accused of killing six people in Alger, Wash., and wounding two others before turning himself into authorities. His mother described him to The Seattle Times as "extremely mentally ill," and authorities said he had been released from jail the month before. Zamora later pleaded guilty to four counts of aggravated first-degree murder and not guilty by reason of insanity to the two other killings. Each of the four murder counts carries a life sentence.
Feb. 2, 2008: Six women were bound with duct tape during a robbery at a Lane Bryant store in the Chicago suburb of Tinley Park, Illinois. Five were shot to death; one was shot and survived. The shooter remains unidentified.
April 16, 2007: In what was then the deadliest shooting incident by a single gunman in American history, Virginia Tech senior Seung-Hui Cho killed 32 and injured 17 at the Blacksburg, Virginia, university before fatally shooting himself. Six more people were injured when they jumped from second-story windows to escape.
April 20, 1999: Students Eric Harris, 18, and Dylan Klebold, 17, shot and killed 12 students and one teacher before committing suicide at Columbine High School near Littleton, Colorado. They also injured another 21 people in the attack, with three more injured while attempting to escape the school. It remains the deadliest high school shooting in U.S. history.
Aug. 20, 1986: Postal worker Pat Sherrill, 44, shot 14 at a post office in Edmond, Okla., before killing himself.
July 12, 1976: California State University custodian Edward Charles Allaway killed seven co-workers and wounded two.
Aug. 1, 1966: Charles Whitman pointed a rifle from the observation deck of the University of Texas at Austin's Tower and began shooting in a homicidal rampage that went on for 96 minutes. Sixteen people were killed and 31 were wounded. Whitman was shot and killed by Austin police officer Houston McCoy.