A U.S. Park Police helicopter removes a man from the Washington Navy Yard on Monday, September 16. At least 12 people were killed in a shooting rampage, according to Washington Police Chief Cathy Lanier. 
Connecticut State Police evacuate children from Sandy Hook Elementary School in Newtown, Connecticut, on December 14, 2012. Adam Lanza opened fire in the school, killing 20 children and six adults before killing himself. Police say he also shot and killed his mother in her Newtown home. 
James Holmes pleaded not guilty by reason of insanity to opening fire June, 20, 2012, at the Century Aurora 16 theater in Aurora, Colorado, during the midnight premiere of "The Dark Knight Rises." Twelve people were killed and dozens were wounded. Holmes is charged with 142 counts, including first-degree murder. His trial is scheduled to begin in February 2014. 
A military jury convicted Army Maj. Nidal Hasan on Friday, August 23, of 13 counts of premeditated murder in a shooting rampage at Fort Hood, Texas. During the November 5, 2009 shooting, 13 people died and 32 were injured. 
Jiverly Wong shot and killed 13 people at the American Civic Association in Binghamton, New York, before turning the gun on himself on April 3, 2009, police say. Four other people were injured at the immigration center shooting. Wong had been taking English classes at the center. 
Pallbearers carry a casket of one of Michael McLendon's 10 victims. McLendon shot and killed his mother in her Kingston, Alabama, home, before shooting his aunt, uncle, grandparents and five more people. He shot and killed himself in Samson, Alabama, on March 10, 2009. McClendon left a note saying he put his mother "out of her misery." 
Virginia Tech student Seung-Hui Cho went on a shooting spree on the campus in Blacksburg, Virginia, on April 16, 2007. Cho killed two people at the West Ambler Johnston dormitory and, after chaining the doors closed, killed another 30 at Norris Hall, home to the Engineering Science and Mechanics Department. He wounded 17 people before killing himself. It is the deadliest shooting rampage in U.S. history. 
Mark Barton walked into two Atlanta trading firms on July 29, 1999, and fired shots, leaving nine dead and 13 wounded, police say. Hours later police found Barton at a gas station in Acworth, Georgia, where he pulled a gun and killed himself. The day before Barton had bludgeoned his wife and his two children in their Stockbridge, Georgia, apartment, police say. The children's birth mother and grandmother had been murdered six years earlier in Alabama. Barton was questioned but never charged in that crime. 
Eric Harris, left, and Dylan Klebold entered Columbine High School in Littleton, Colorado, on April 20, 1999, armed with bombs and guns. The students killed 13 and wounded 23 before killing themselves. 
George Hennard crashed his pickup through the plate glass window of Luby's Cafeteria in Killeen, Texas, on October 16, 1991, before fatally shooting 23 people and committing suicide. 
James Huberty shot and killed 21 people, including children, at a McDonald's in San Ysidro, California, on July 18, 1984. A police sharpshooter killed Huberty an hour after the rampage began. 
Prison guard George Banks is led through the Luzerne County courthouse in 1985. Banks killed 13 people, including five of his children, in Wilkes-Barre, Pennsylvania, on September 25, 1982. He was sentenced to death in 1993 and received a stay of execution in 2004. His death sentence was overturned in 2010. 
Officers carry victims across the University of Texas at Austin campus after Charles Joseph Whitman opened fire from the school's tower, killing 16 people and wounding 30. Police officers shot and killed Whitman, who had killed his mother and wife earlier in the day. 
Howard Unruh, a World War II veteran, shot and killed 13 of his neighbors on September 5, 1949, In Camden, New Jersey. Unruh barricaded himself in his house after the shooting. Police overpowered him the next day. He was ruled criminally insane and committed to a state mental institution. 
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(CNN) -- Here is a list of the 20 deadliest mass shootings in U.S. history from 1965 to the present. If the shooter was killed or committed suicide during the incident that death is not included in the total.
Timeline: 32 killed - April 16, 2007 - Virginia Tech in Blacksburg, Virginia. A gunman, 23-year-old student Seung-Hui Cho, goes on a shooting spree killing 32 people in two locations and wounds an undetermined number of others on campus. The shooter, Seung-Hui Cho then committed suicide.
27 killed - December 14, 2012 - Sandy Hook Elementary School - Newtown, Connecticut. Adam Lanza, 20, guns down 20 children, ages 6 and 7, and six adults, school staff and faculty, before turning the gun on himself. Investigating police later find Nancy Lanza, Adam's mother, dead from a gunshot wound. The final count is 28 dead, including the shooter.
23 killed - October 16, 1991 - In Killeen, Texas, 35-year-old George Hennard crashes his pickup truck through the wall of a Lubys Cafeteria. After exiting the truck, Hennard shoots and kills 23 people. He then commits suicide.
21 killed - July 18, 1984 - In San Ysidro, California, 41-year-old James Huberty, armed with a long-barreled Uzi, a pump-action shotgun and a handgun shoots and kills 21 adults and children at a local McDonalds. A police sharpshooter kills Huberty one hour after the rampage begins.
18 killed - August 1, 1966 - University of Texas. Charles Joseph Whitman, a former U.S. Marine, kills 16 and wounds at least 30 from a university tower. Police officers Ramiro Martinez and Houston McCoy shot and killed Whitman in the tower. Whitman had also killed his mother and wife earlier in the day.
13 killed - November 5, 2009 - Maj. Nidal Malik Hasan kills 13 people and injures 32 at Fort Hood, Texas, during a shooting rampage. He is convicted and sentenced to death.
13 killed - April 3, 2009 - In Binghamton, New York, Jiverly Wong kills 13 people and injures four during a shooting at an immigrant community center. He then kills himself.
13 killed - April 20, 1999 - Columbine High School - Littleton, Colorado. 18-year-old Eric Harris and 17-year-old Dylan Klebold kill 12 fellow students and one teacher before committing suicide in the school library.
13 killed - September 25, 1982 - In Wilkes-Barre, Pennsylvania, 40-year-old George Banks, a prison guard, kills 13 people including five of his own children. In September 2011, the Pennsylvania Supreme Court overturns his death sentence stating that Banks is mentally incompetent.
12 killed - September 16, 2013 - Shots are fired inside the U.S. Navy Yard killing 12. The shooter, identified as Aaron Alexis, 34, is also killed.
12 killed - July 20, 2012 - Twelve people are killed and 58 are wounded in a shooting at an Aurora, Colorado, movie theater screening of the new Batman film. James E. Holmes, 24, is taken into custody outside of the movie theater. The gunman is dressed head-to-toe in protective tactical gear, set off two devices of some kind before spraying the theater with bullets from an AR-15 rifle, a 12-gauge shotgun and at least one of two .40-caliber handguns police recovered at the scene.
12 killed - July 29, 1999 - In Atlanta, Georgia, 44-year-old Mark Barton kills his wife and two children at his home. He then opens fire in two different brokerage houses killing nine people and wounding 12. He later kills himself.
10 killed - March 10, 2009 - In Alabama, Michael McLendon of Kinston, kills 10 and himself. The dead include his mother, grandparents, aunt and uncle.
9 killed - January 7, 1973 - In New Orleans, Louisiana, 23-year-old Mark Robert James Essex, using a .44 magnum carbine, kills nine people in a rampage at a Howard Johnson motel. Police snipers later kill him.
8 killed - October 12, 2011 - Eight people are killed during a shooting at the Salon Meritage in Seal Beach, California. The suspect, Scott Evans Dekraai, 41, of Huntington Beach, is arrested without incident as he is trying to leave the scene. The eight dead include Dekraai's ex-wife, Michelle Fournier, 48.
8 killed - August 3, 2010 - Manchester, Connecticut - Omar Thornton kills eight co-workers at Hartford Distributors before turning the gun on himself. Thornton had been asked to resign for stealing and selling alcoholic beverages.
8 killed - January 19, 2010 - Christopher Speight, 39, kills eight people at a house in Appomattox, Virginia. He surrenders to police at the scene the next morning, and is charged with one count of murder with additional charges pending.
8 killed - March 29, 2009 - In Carthage, North Carolina, 45-year-old Robert Stewart kills a nurse and seven elderly patients at a nursing home. In May, the Moore County district attorney announces she will seek the death penalty. On September 3, 2011, a jury finds Stewart guilty of second-degree murder. Stewart is sentenced to 141 to 179 years in prison.
8 killed - December 5, 2007 - In Omaha, Nebraska, 19-year-old Robert Hawkins goes to an area mall and kills eight shoppers before killing himself.
8 killed - March 21, 2005 - Red Lake High School, Red Lake, Minnesota. 16-year-old Jeff Weise kills his grandfather and another adult, four fellow students, a teacher and a security officer. He then killed himself.
8 killed - July 1, 1993 - In San Francisco, California, 55-year-old Gian Luigi Ferri kills eight people in a law office and then kills himself.
8 killed - September 14, 1989 - In Louisville, Kentucky, 47-year-old Joseph Wesbecker armed with a AK-47 semiautomatic assault rifle, two MAC-11 semiautomatic pistols, a .38 caliber handgun, a 9-millimeter semiautomatic pistol and a bayonet kills eight co-workers at Standard Gravure Corporation and then kills himself. He was placed on disability leave from his job due to mental problems.
8 killed - May 17, 1984 - In Manley Hot Springs, Alaska, 25-year-old drifter Army veteran Michael Silka kills eight people in a three-hour rampage. Two days later, Silka is killed in a shootout with police.
8 killed - August 20, 1982 - In Miami, Florida, 51-year-old history teacher Carl Robert Brown, angry about a repair bill and armed with a shotgun, kills eight people at a machine shop. He flees by bicycle, but is shot on the back by a witness who pursued him. He was on leave from school for psychological treatment.
