Dec. 14, 2012: 20-year-old Adam Lanza fatally shot 20 children and six adult staff members at Sandy Hook Elementary School in Newtown, Conn. Earlier, he had killed his mother Nancy at their Newtown home.
Dec. 11, 2012: 22-year-old Jacob Tyler Roberts killed two people and himself with a stolen rifle in Clackamas Town Center, Oregon. His motive is unknown.
Sept. 27, 2012: Five were shot to death by 36-year-old Andrew Engeldinger at Accent Signage Systems in Minneapolis, Minn. Engeldinger ended up killing himself in the rampage over losing his job.
Aug. 5, 2012: Six Sikh temple members were killed when 40-year-old Army veteran Wade Michael Page opened fire in Oak Creek, Wisconsin. Page killed himself as cops moved in.
July 20, 2012: During the midnight premiere of “The Dark Knight Rises” in Aurora, Colo., 24-year-old James Holmes killed 12 people and wounded 58.
May 29, 2012: Ian Stawicki opened fire on Cafe Racer Espresso in Seattle, Wash., killing five and himself after a citywide manhunt.
April 6, 2012: Jake England, 19, and Alvin Watts, 32, shot five black men in Tulsa, Okla., in racially motivated shooting spree. Three died.
April 2, 2012: A former student, 43-year-old One L. Goh killed seven people at Oikos University, a Korean Christian college in Oakland, Calif.
Feb. 27, 2012: Three students were killed by Thomas "TJ" Lane in a rampage at Chardon High School in Ohio.
Oct. 14, 2011: Eight people died when 41-year-old Scott Evans Dekraai shot up the Salon Meritage hair salon in Seal Beach, Calif.
Sept. 6, 2011: Eduardo Sencion, 32, entered an IHOP restaurant in Carson City, Nev. and shot 12 people. Five died.
Jan. 8, 2011: Jared Loughner, 22, opened fire at a Safeway market in Tucson, Ariz. Six people died, and then-Rep. Gabby Giffords was badly injured.
Aug. 3, 2010: Omar Thornton, 34, gunned down Hartford Beer Distributor in Manchester, Conn. after getting caught stealing beer. Nine were killed, including Thornton.
Nov. 5, 2009: Forty-three people were shot by Army psychiatrist Nidal Malik Hasan at the Fort Hood army base in Texas. Thirteen were killed and 29 were wounded.
April 3, 2009: Jiverly Wong, 41, opened fire at an immigration center in upstate Binghamton before committing suicide. He killed 13 people and wounded 4.
March 29, 2009: Eight people died in a shooting at the Pinelake Health and Rehab nursing home in Carthage, N.C. The gunman, 45-year-old Robert Stewart, was targeting his estranged wife.
Feb. 14, 2008: Steven Kazmierczak, 27, opened fire in a lecture hall at Northern Illinois University, killing six and wounding 21.
Feb. 7, 2008: Six people died and two were injured in a shooting spree at the City Hall in Kirkwood, Missouri. The gunman, Charles Lee Thornton, opened fire during a public meeting after being denied construction contracts he believed he deserved. Thornton was killed by police.
Dec. 5, 2007: A 19-year-old boy, Robert Hawkins, shot up a department store in Omaha, Neb. Hawkins killed nine people and wounded four before killing himself.
April 16, 2007: Virginia Tech became the site of the deadliest school shooting in U.S. history when a student, Seung-Hui Choi, gunned down 56 people. Thirty-two people died.
Feb. 12, 2007: Five people were shot to death in Salt Lake City by 18-year-old gunman Sulejman Talovic.
Oct. 2, 2006: An Amish schoolhouse in Lancaster, Penn. was gunned down by 32-year-old Charles Carl Roberts, who separated the students by gender before killing five girls. Roberts committed suicide afterward.
March 25, 2006: Seven died and two were injured by 28-year-old Kyle Aaron Huff in a shooting spree through Seattle, Wash.
March 21, 2005: Teenager Jeffrey Weise killed his grandfather and his grandfather’s girlfriend before opening fire on Red Lake Senior High School, killing nine people on campus, plus himself.
March 12, 2005: Terry Michael Ratzmann, a member of the Living Church of God, shot up a service at a hotel in Brookfield, Wisc. Ratzmann killed himself after executing the pastor, the pastor’s 16-year-old son, and seven others.
July 8, 2003: Doug Williams shot up a Lockheed plant in Meridian, Miss. in a racially motivated rampage, killing seven before taking his own life.
Dec. 26, 2000: Edgewater Technology employee Michael McDermott shot and killed seven of his coworkers at the office in Wakefield, Mass. McDermott claimed he had “traveled back in time and killed Hitler and the last six Nazis.”
Sept. 15, 1999: Larry Gene Ashbrook opened fire on a Christian rock concert and teen prayer rally in Fort Worth, Tex. He killed seven people and wounded seven others, almost all teenagers. Ashbrook committed suicide.
July 29, 1999: Mark Orrin Barton, 44, murdered his wife and two children with a hammer before shooting up two Atlanta day trading firms. Barton was believed to be motivated by huge monetary losses. He killed 12 including his family and injured 13 before killing himself.
April 20, 1999: Teenagers Eric Harris and Dylan Kiebold shot up Columbine High School in Colorado. They killed 13 people and wounded 21 others. They killed themselves after the massacre.