The United States on Tuesday witnessed its second deadly mass shooting in a week after a gunman killed 10 people in a grocery store in Boulder, Colorado. However, this is not the first time such a thing happened in the state.

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Colorado has been the scene of several mass shootings in recent years and according to The New York Times, these six firings have dominated the national headlines:

May 7, 2019:

Two students fired at fellow students at a charter school in Highlands Ranch and wounded nine of them. They were later captured.

December 31, 2017:

A man barricaded himself in an apartment in Highlands Ranch and engaged in a gunfight with police. One officer was killed and four were injured. The police eventually killed the gunman. Two civilians were also wounded.

Also read: Who was Eric Talley? The police officer killed in Boulder shooting

November 27, 2015:

A man killed two civilians and a police officer in an open fire at the Planned Parenthood clinic in Colorado Springs. Nine others were injured in a five-hour siege before the armed man surrendered.

October 31, 2015:

A man killed three people on a residential street near downtown Colorado Springs and was confronted and shot dead by police.

Also read: 'He said nothing before raising the gun': Eyewitnesses on Colorado shooter

July 20, 2012:

During a midnight screening of a Batman film, a man walked to the front of a crowded movie theatre in Aurora, set off tear gas grenades and opened fire. He killed 12 people and wounded 70 others. The gunman was arrested in the theatre parking lot.

April 20, 1999:

Two students shot a teacher and 12 fellow students at Columbine High School in Littleton. They then killed themselves.