The violence one week ago at Sandy Hook Elementary School was horrific, you might say incomprehensible. But mass shootings no longer qualify as unusual in the United States.
According to a list compiled by the Washington Post, there have been 13 this year alone, about one every four weeks.
Feb. 21: Jeong Soo Paek killed his two sisters, their husbands and himself in a family-owned spa in Norcross, Ga.
Feb. 27: T.J. Lane, a 17-year-old high school students, is accused of shooting five people, killing three, in a high school cafeteria in Chardon, Ohio.
March 8: John Shick, a former teaching assistant at Duquense University in Pittsburgh, shot eight people, killing one, as he walked through a psychiatric hospital. He was shot by police.
April 2: One Goh, a former nursing student at Oikos University in Oakland, is accused of lining people up against a wall and shooting them. Seven people died, three more were wounded.
April 6: Jake England and Alvin Watts randomly targeted black men as they drove around Tulsa, Okla. on Easter weekend, according to police. Three people were killed, two more were wounded.
May 30: Ian Stawicki stood up and started shooting after he was asked to leave a Seattle coffee shop. Five people were killed, one was injured. Stawicki later killed himself.
July 20: James Holmes, a graduate student dressed as a character from Batman, allegedly opened fire during a midnight screening of "The Dark Knight Rises" in an Aurora, Colo. movie theater. Twelve people died, 58 were wounded.
Aug. 5: Wade Page killed five people and wounded three others shortly before Sunday services in a Sikh temple in Oak Creek, Wis. He then killed himself.