In what turned out to be the worst mass shooting in the history of modern US, a gunman opened fire on the 32nd floor of a Las Vegas casino on an outdoor music festival, killing at least 50 people and more than 200 wounded.
The police neutralised the lone attacker, 64-year-old local resident Stephen Paddock.
While the federal government doesn't define a mass shooting, it is commonly defined as a case where four or more people are killed or injured. The FBI defines a mass killing as an incident resulting in the killing of three or more in a public space.
The shooting has once again prompted a national debate questioning the laws related to gun licensing in the United States.
Here is a list of the deadliest single day mass shootings the country has ever seen:
Orlando, 2016 – 50 killed
An America-born man Oman Mateen opened fire inside a gay nightclub in Orlando on June 12, 2016, killing 49 people and leaving 58 others injured. Police shoot shot dead Mateen during an operation to free hostages he was holding at the club.
In a 9-1-1 call shortly after the shooting began, Mateen swore allegiance to the leader of the Islamic State of Iraq and the Levant (ISIL), Abu Bakr al-Baghdadi, and said the shooting was "triggered" by the U.S. killing of Abu Waheeb in Iraq the previous month.
Virginia Tech, 2007 – 32 killed
A gunman, 23-year-old student Seung-Hui Cho, went on a shooting spree, killing 32 people in two shooting scenes at a dorm and then in a classroom building on the Virginia Tech campus in Blacksburg, Virginia. He then killed himself.
Sandy Hook, 2012 – 27 killed
The Sandy Hook Elementary School shooting occurred on December 14, 2012, in Newtown, Connenticut. 20-year-old Adam Lanza gunned down 20 children between six and seven years old, as well as six adult staff members. Prior to driving to the school, he shot and killed his mother at their Newtown home.
As first responders arrived at the scene, Lanza committed suicide by shooting himself in the head.
San Ysirdo, 1984 – 21 killed
In San Ysirdo, 41-year-old James Huberty, armed with a long-barrelled Uzi, a pump-action shotgun and a gun, shot and killed 21 adults and children at a local McDonald’s. The lone attacker was later shot dead by a police sharpshooter.
San Bernardino, 2015 – 14 killed
14 people were killed and 22 others were seriously injured in a terrorist attack consisting of a mass shooting and an attempted bombing at the Inland Regional Center in San Bernardino. The mass shooting at the employee gathering was carried out by a married couple Syed Rizwan Farook and Tashfeen Malik.
After the shooting, the couple fled in a rented sport utility vehicle (SUV). Four hours later, police pursued their vehicle and killed them in a shootout.
Edmond, 1986 – 14 killed
In Edmond, Oklahoma, part-time mail carier Patrick Henry Sherrill, armed with three handguns killed 14 postal workers in 10 minutes before taking his own life with a bullet to the head.
Fort Hood, 2009 – 13 killed
Thirteen people – including soldiers and civilians – were killed and more than two dozen wounded when a gunman walked into the Soldier Readiness Processing Center at Fort Hood, Texas, and opened fire.
Identified as Maj. Nidal Hasan, the gunman was an Army psychiatrist. He was convicted on 13 counts of premeditated murder and hanged to death.
Columbine, 1999 – 13 killed
On April 20, 1999, two teens went on a shooting spree at Columbine High School in Littleton, Colorado, killing 13 people and wounding at least 20 others before turning guns on themselves and committing suicide.
Binghamton, 2009 – 13 killed
A gunman identified as 41-year-old Jiverly Wong opened fire in a community centre where immigrants were taking a citizenship exam in Binghamton, in upstate New York, killing 13 people before committing suicide.
