Sandy Hook Elementary School shooting

On the morning of December 14, 2012, Adam Lanza, 20, shot and killed his mother, Nancy Lanza, 52, at their home in Newtown, Connecticut, using a .22-caliber rifle. He then drove her car to Sandy Hook Elementary School, where 456 children were enrolled in kindergarten through fourth grade. Shortly after 9:35 a.m., Lanza shot his way through a glass panel beside the school's locked front entrance, armed with a Bushmaster XM15-E2S rifle and ten 30-round magazines.

Inside the school, Lanza killed Principal Dawn Hochsprung and school psychologist Mary Sherlach in a hallway after they confronted him, and wounded lead teacher Natalie Hammond. He entered two first-grade classrooms, Room 8 and Room 10, where most of the killing occurred. In Room 8, substitute teacher Lauren Rousseau, behavioral therapist Rachel D'Avino, and 15 students were killed; one child survived by hiding. In Room 10, teacher Victoria Leigh Soto, special education teacher Anne Marie Murphy, and several students were killed, while some children escaped during the attack. Other staff, including nurse Sarah Cox, secretary Barbara Halstead, and janitor Rick Thorne, hid or helped alert classrooms. Several teachers barricaded students in bathrooms, closets, and storage rooms, actions credited with saving lives.

Police arrived within minutes; Newtown police entered the school at 9:45 a.m., about five minutes after the last shot was heard. Officers reported no shots fired by police. As first responders arrived, Lanza killed himself with a gunshot to the head using a Glock 20SF handgun in Room 10. In total, Lanza fired 156 shots in under five minutes. Investigators found a 12-gauge shotgun locked in Lanza's car and additional unused firearms and ammunition at the school and at his home.

The Connecticut State Attorney's November 2013 report concluded Lanza acted alone and planned the attack but found no clear motive. A November 2014 report by the Office of the Child Advocate noted Lanza had Asperger's syndrome, depression, anxiety, obsessive-compulsive disorder, and anorexia, but stated these conditions "neither caused nor led to his murderous acts," instead describing a combination of deteriorating mental health, isolation, and access to weapons as contributing factors.

The shooting led to lawsuits, including one by families against Nancy Lanza's estate, settled in 2015, and a lawsuit against gun manufacturer Remington and related companies, settled for $73 million in 2022. Separate defamation lawsuits were brought by victims' family members against author James Fetzer and broadcaster Alex Jones over false claims that the shooting was fabricated; both were found liable for defamation, with Jones ordered to pay over $1.4 billion in combined judgments across two cases. The event prompted national debate over gun control, mental health policy, and school security, and remains one of the deadliest school shootings in U.S. history.