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.
Florida club: 49 killed
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 shoot-out with police; he pledges allegiance to Islamic State, which later claims responsibility.
Virginia Tech: 32 killed
Cho Seung-hui, 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.
Sandy Hook: 26 killed
A disturbed 20-year-old man named Adam Lanza 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.
Texas restaurant: 22 dead
In October 1991 a man shoots dead 22 people in a restaurant in the town of Killeen and then kills himself.
California office party: 14 dead
A newlywed radicalised Muslim couple storm an Christmas office party at a social services centre in San Bernardino in December 2015 and gun down 14 people, wounding 22 others. They are shot dead by police.
Fort Hood military base: 13 dead
In November 2009 US army psychiatrist Nidal Hasan opens fire at his military base in Killeen, killing 13 people and wounding 42, before being overpowered by police.
New York immigrant centre: 13 dead
A Vietnamese immigrant shoots dead 13 people at a civic centre in the New York state city of Binghamton in April 2009, before killing himself.
Marines: 12 dead
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.
Denver cinema: 12 dead
James Holmes, a young man wearing body armour storms a cinema showing a late-night premiere of a Batman film in Aurora in July 2012, opening fire and releasing tear gas. Twelve people and 70 wounded. He is sentenced to life in prison.
Columbine High: 12 dead
Two teenage boys, Eric Harris and Dylan Klebold, shoot and kill 12 classmates and a teacher at Columbine High School in Littleton, Colorado, in April 1999, before killing themselves.