Orlando shooting: Know why Florida nightclub attack was deadliest in US history

New York: Fifty people were killed and 53 others injured on Sunday when an Islamic State (IS) gunman opened fire at a gay nightclub in Orlando, Florida.

Xinhua news agency compiled the major shooting incidents in the US that caused deadly casualties in the past decades. 

On June 12, 2016: A gunman killed at least 50 people and injured 53 at the Pulse nightclub in Orlando, Florida.

On April 16, 2007: A 23-year-old student from the Republic of Korea went on a shooting spree at Virginia Tech University in Blacksburg of Virginia, killing 32 people and wounding 15 others before killing himself. It was the worst school shooting in the US history.

On December 14, 2012: A 20-year-old Adam Lanza killed 28 people including 20 children and eight adults in Sandy Hook Elementary School in the US state of Connecticut. Lanza first killed his mother at their shared home before taking her guns and driving to the school. 

On October 16, 1991: A 35-year-old gunman crashed his truck through the wall of a Cafeteria in Kileen, Texas and shot dead 23 people and wounded 27 others. He then committed suicide.

On July 18, 1984: A 41-year-old gunman killed 21 adults and children at a local McDonalds in San Ysidro, California before he was killed by a SWAT team sniper.

On August 1, 1966: A former US Marine killed 14 and wounded at least 30 while shooting from a University of Texas tower in Austin, Texas. Police officers shot the gunman dead in the tower. Before he went on the shooting, he murdered his wife and his mother in their homes.

On December 2, 2015: A married couple shot 14 people dead and wounded 17 in a conference hall at a service centre for disabled people where county employees gathered for a celebration in San Bernardino, California.

On August 20, 1986: A part-time mail carrier armed with three handguns killed 14 postal workers in Edmond, Oklahoma in 10 minutes before killing himself.

On November 5, 2009: Major Nidal Malik Hasan killed 13 people and injured 32 at Fort Hood, Texas in a shooting rampage. He was convicted and sentenced to death.

On April 3, 2009: Jiverly Wong killed 13 people and injured four during a shooting at an immigrant community centre in Binghamton, New York and then took his own life.

On April 20, 1999: Two teenagers killed 12 fellow students and a teacher before committing suicide in the school library in Columbine High School in Littleton, Colorado.

On February 18, 1983: Three men entered the Wah Mee gambling and social club in Seattle, Washington, robbed the 14 occupants and shot 13 of them dead.

On September 16, 2013: Thirty four-year-old Aaron Alexis fired inside the Washington Navy Yard, killing 12. He was also killed in the shooting.

On July 20, 2012: A heavily-armed 24-year-old gunman killed 12 people and 58 wounded in a shooting at a movie theatre in Aurora, Colorado.

On March 10, 2009: Michael McLendon of Kinston killed 10 people including his mother, grandparents, aunt and uncle, and then committed suicide.

An average of about 33,000 people were killed by guns each year in the US in the past five years, according to the data released by the US Central of Disease Control.

Reports said that during Obama's seven and half years in office, he has come out to address a major shooting tragedy for a total of 15 times.