After a gunman killed more than 50 people at a Las Vegas concert Sunday, here are some of the deadliest mass shootings in the United States in the past 25 years.
A heavily-armed gunman opens fire inside a gay nightclub in the city of Orlando on June 12, 2016 and kills 49 people.
The attacker is killed in a shootout with police; he pledges allegiance to the Islamic State group, which later claims responsibility.
A 23-year-old student of Korean origin goes on a rampage at Virginia Tech University in the town of Blacksburg in April 2007. He kills 27 students and five teachers before committing suicide.
A disturbed 20-year-old man kills his mother in Newtown, Connecticut, in December 2012 before blasting his way into Sandy Hook Elementary School and shooting dead 20 six- and seven-year old children and six adults. He commits suicide.
In October 1991 a man shoots dead 22 people in a restaurant in the town of Killeen, Texas and then kills himself. Another wounded victim dies later.
A newlywed radicalized Muslim couple storm a Christmas office party at a social services center in San Bernardino in December 2015 and gun down 14 people, wounding 22 others. They are shot dead by police.
In November 2009 a US army psychiatrist opens fire at his military base in Killeen, Texas, killing 13 people and wounding 42, before being overpowered by police.
A Vietnamese immigrant shoots dead 13 people at a civic center in the New York state city of Binghamton in April 2009, before killing himself.
Two teenage boys shoot and kill 12 classmates and a teacher at Columbine High School in Littleton, Colorado, in April 1999, before killing themselves.
A troubled former serviceman shoots randomly at workers at the Washington Navy Yard headquarters in September 2013, killing 12 people before he is shot dead by officers.
A young man wearing body armor storms a cinema showing a late-night premiere of a Batman film in Aurora, Colorado in July 2012, opening fire and releasing tear gas. Twelve people and 70 wounded. He is sentenced to life in prison.