Newsweek has released the names of the 4 mass shootings in Colorado in 2014 that did not occur in 2014.
Included in the list is a massacre at the University of Colorado Springs, which left 12 dead and 29 wounded, as well as an attack at a gas station in Greeley, which killed nine and wounded 20.
Other mass shootings occurred in 2015, including a mass shooting at a movie theater in Aurora, Colorado, in which James Holmes, the suspect in the Aurora mass shooting, killed 12 and wounded 70 others, and a shooting in Las Vegas that killed 59 people.
Newsweek was first to report the list.
The shooting in Colorado Springs left 12 people dead and 79 wounded, and in Las Angeles, authorities found an active shooter who shot at law enforcement officers and killed himself, authorities said.
In a separate shooting at the Los Angeles County Fairgrounds, a man who was arrested for an alleged hate crime killed himself after an officer opened fire.
In Colorado Springs and Las Vegas, the killings were linked to a gunman who opened fire on a crowd of people attending a birthday party.
He was killed by police.