Mass shootings in 2012

A mass shooting at Sandy Hook Elementary School in Newtown, Conn. left 27 people dead, including 20 children and the gunman, on Dec. 14, 2012. The gunman, identified as 20-year-old Adam Lanza, reportedly had three guns on him, including an AR-15 semiautomatic rifle. Lanza killed himself in the school. After the shooting, it was discovered that Lanza had also shot and killed his mother, Nancy Lanza, in the home they shared.

Police and medics work the scene of a multiple shooting at Clackamas Town Center Mall in Clackamas, Ore., Tuesday Dec. 11, 2012. A gunman is dead after opening fire in the Portland, Ore., area shopping mall Tuesday, killing two people and wounding another — AP Photo/Greg Wahl-Stephens

Police and medics work the scene of a multiple shooting at Clackamas Town Center Mall in Clackamas, Ore., Tuesday Dec. 11, 2012. The alleged gunman, Jacob Tyler Roberts, 22, is dead after opening fire in the Portland, Ore., area shopping mall Tuesday, killing two people and wounding another, sheriff's deputies said.

Jacob Tyler Roberts, 22, is suspected of opening fire inside the Clackamas Town Center Mall in Clackamas, Ore., on Tuesday, Dec. 11. Roberts allegedly killed two people and then himself.

Aurora Theater Shooting

Police are pictured outside of a Century 16 movie theatre where 12 were killed and 58 people were injured at a shooting during the showing of the new Batman movie "The Dark Knight Rises" at the in Aurora, Colo., July 20, 2012. James Holmes, a former graduate student at the University of Colorado, Denver, has been charged in the shootings. He is in prison in Colorado.

Aurora Theater Shooting

The booking photo of James Eagan Holmes released by the Arapahoe County Sheriff's Office in Centennial, Colorado. The picture was taken hours after a shooting massacre at an Aurora, Colo. movie theater that killed 12 and injured 58 people on July 20, 2012.

Chardon High School Shooting

Investigators congregate at a rear entrance to Chardon High School in Chardon, Ohio Monday, Feb. 27, 2012. A gunman opened fire inside the high school's cafeteria at the start of the school day Monday, killing three and wounding three others. Special Agent Vicki Anderson said Monday the shooter was taken into custody near his car about half a mile (one kilometer) away from the high school.

Chardon High School Shooting

Seventeen-year-old TJ Lane is led from Juvenile Court by sheriff's deputies in Chardon, Ohio, Feb. 28, 2012, after his arraignment in the shooting of five high-school students. — AP Photo

Seventeen-year-old TJ Lane is led from Juvenile Court by sheriff's deputies in Chardon, Ohio, Feb. 28, 2012, after his arraignment in the shooting deaths of three students.

Tulsa County Courthouse Shooting

Andrew Dennehy holds a gun as sheriff's deputies and other law enforcement surround him at the Tulsa County Courthouse in Tulsa, Okla. on March 7, 2012.

Western Psychiatric Institute Shooting

Police help employees of Western Psychiatric Institute and Clinic evacuate the building March 8, 2012, in Pittsburgh. — AP Photo/Pittsburgh Tribune-Review

Police help employees of Western Psychiatric Institute and Clinic in Pittsburgh evacuate the building March 8, 2012 after a gunman opened fire inside

Western Psychiatric Institute Shooting

John Shick, the alleged gunman in the Pittsburgh shooting, was killed by police

Oikos University Shooting

The entrance to Oikos University is shown after a school shooting in Oakland, Calif., Monday, April 2, 2012. A gunman opened fire at the university, killing seven people.

Oikos University

One Goh appears in an Alameda County Superior courtroom in Oakland, Calif., Monday, April 30, 2012. Goh, 43, plead not guilty to seven counts of murder and three counts of attempted murder for the fatal shooting rampage at Oikos University in Oakland on April 2, 2012.

Cafe Racer Shooting

A Seattle Police officer stands outside Cafe Racer, where Ian Stawicki allegedly opened fire on Wednesday, May 30, 2012.

Cafe Racer Shooting

Seattle police released surveillance photos of the man suspected of killing four people and wounding 1 other at a North Seattle cafe.

Alabama Bar Shooting

In this Tuesday, July 17, 2012 image captured from video and provided by the Tuscaloosa Police Department, a gunman walks near a Tuscaloosa, Ala., bar. Tuscaloosa police say 17 people were wounded when a gunman opened fire in a crowded bar in downtown Tuscaloosa.

Alabama Bar Shooting

Nathan Van Wilkins, above, is accused of attempted murder in the shooting at a Tuscaloosa, Ala. bar in the early morning on Tuesday, July 17, 2012.

Sikh Temple Shooting

The scene outside the Sikh Temple of Wisconsin in Oak Creek, where seven people were shot dead, Sunday, August 5, 2012.

Sikh Temple Shooting

The mug shot handed out by the FBI of the suspect Wade Michael Page after a press conference on the shooting at the Sikh Temple of Wisconsin where a gunman fired upon people at service August, 6, 2012 in Oak Creek, Wisconsin.

This photo provided by the Brookfield Police Dept. shows Radcliffe Franklin Haughton, 45, of Brown Deer, Wis. Police say Haughton shot and killed three people and wounded four others at a suburban Milwaukee spa on Sunday, Oct. 21, 2012. After a search for Haughton, whose wife worked at the salon, police found the alleged gunman dead of an apparent self-inflicted gunshot wound inside a locked area of the salon. Police say Haughton had a history of domestic violence.

Police said 42-year-old ex-convict Lawrence Jones pulled a gun a California chicken processing plant he was working at and opened fire at his co-workers on Nov. 6, 2012. He killed two people and wounded two others before taking his own life, authorities said.

Police search the area around Valley Protein, the chicken processing plant where Lawrence Jones fatally shot two people and wounded two others before taking his own life on Nov. 6, 2012 in Fresno, Calif.