Here is an overview of some of the deadliest mass shootings in the United States in the past three decades.
Las Vegas concert: 58 killed
A 64-year-old man whose father had been on the FBI's most wanted list in the late 1960s shoots down from his hotel room at a crowd attending an outdoor country music concert on October 1, 2017, killing 58 people and wounding some 546 before committing suicide. It is the worst mass shooting in modern US history.
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 shootout with police; he pledges allegiance to the Islamic State group, which later claims responsibility.
Virginia Tech: 32 killed
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 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.
Florida high school shooting: 17 killed
On February 14, 2018, 19-year-old Nikolas Cruz, a former student of the Marjory Stoneman Douglas High School in Parkland, Florida, opened fire at the school killing 17 people. The rampage was one of the deadliest school shootings in modern US history.
Prosecutors will seek the death penalty for Cruz, who has admitted to carrying out the attack.
California office party: 14 dead
A newlywed radicalized 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 a US army psychiatrist 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.
California bar: 12 dead
A 28-year-old Marine Crops veteran killed 12 people in a country bar packed with college students in California on 8 November 2018.
Terrified patrons ran out the back door and smashed windows in an attempt to escape before the shooter was found dead.
Denver cinema: 12 dead
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 shoot and kill 12 classmates and a teacher at Columbine High School in Littleton, Colorado, in April 1999, before killing themselves.
Washington Navy Yard: 12 dead
A 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.
Pittsburgh synagogue: 11 dead
A shooter killed 11 people and injured six in the deadliest attack on Jews in American history.
The 46-year-old shooter armed with an AR-15 assault rifle and three handguns killed 11 worshippers at a synagogue in Pittsburgh.