UPDATED at 4:45 p.m.: Last night's random shooting into a Colorado movie theater represents a tragedy with which Americans are becoming familiar. So far this year, at least six other random mass shootings have taken place in the United States.
This does not include incidents where the victims knew the shooter or were caught in shooting related to previous disputes or arguments, such as the Arizona man who in May fatally shot his girlfriend and three others before turning a gun on himself after a domestic dispute.
A Huffington Post analysis of FBI crime data showed that while single-victim shootings have declined 40% over the last three decades, mass shootings have ticked upward slightly in recent years.
2012 - Mass random shootings
July 19, Aurora, Colo: Gunman shoots into a movie theater, killing 12 and injuring 50 others.
July 17, Tusaloosa, Ala: Gunman shoots into a bar, injuring 17.
May 30, Seattle, Wash: Gunman shoots into cafe and later carjacks a woman, killing five and injuring one others.
April 7, Tulsa, Okla: Two gunmen accused of shooting passersby in a north Tulsa neighborhood, killing three and injuring two others.
April 2, Oakland, Calif: Gunman opens fire on classroom at Oikos University, killing seven and injuring three others.
March 3, Pittsburgh, Pa.: A gunman opens fire on a psychiatric hospital in Pittsburgh, killing one person and injuring seven more.
February 27, Chardon, Ohio: Teenager shoots into high school cafeteria, killing three and injuring three others.
Other recent mass shootings in the United States
January 8, 2011, Tucson, Ariz: Rep. Gabrielle Giffords, D-Ariz., was shot in the head during a constituent event. Six people were killed, 13 wounded when a shooter mowed down the crowd with a semiautomatic weapon equipped with a 33-round magazine.
November 5, 2009, Fort Hood, Texas: Gunmen goes on a shooting rampage at a military base, killing 12 people and wounding 31.
April 3, 2009, Binghampton, NY: Jiverly Wong opened fire into a community center, killing 13 people before turning the gun on himself.
March 10, 2009, Samson, Ala: Michael McLendon committed suicide after a killing rampage that left 10 people dead - including his mother and four relatives - and spanned two counties.
April 16, 2007, Virginia Tech: In the worst U.S. shooting ever, Seung-Hui Cho, 23, opened fire on the Virginia Tech campus, killing himself and 32 others, wounding 17.
October 2002, Washington, D.C., region: A sniper terrorizes the country's capital by killing people at random from a car. Ten people are killed while at gas stations and other locations and six others are injured. John Allen Muhammad was later executed for the killings, and his teenage accomplice, Lee Boyd Malvo, was sentenced to back-to-back life sentences without parole.
April 20, 1999, Columbine, Colo: Teenagers Eric Harris and Dylan Klebold opened fire on Columbine High School, killing 12 students and one teacher before taking their own lives.
With additional research from Amanda Sakuma