The man authorities say killed 27 people in Connecticut was a reserved and intelligent 20-year-old who suffered from a mental disability, police and people who knew him said.
Adam Lanza committed the second-worst mass shooting in US history, killing 20 children, six adults and himself after he walked into Sandy Hook Elementary School in Newtown and opened fire, according to two law-enforcement officials briefed on the matter. His mother, Nancy, was found dead at their home, according to the officers, who asked for anonymity because the investigation is continuing.
The shooting brought chaos and worldwide attention to the town of 28,000 about 60 miles (97 kilometers) northeast of New York City. Students recounted cowering in the corners of the school of 700, while parents told of rushing to discover whether their children were among the dead. Officials have yet to announce a motive.
"As a country, we have been through this too many times," President Barack Obama said in a news conference, struggling to hold back tears. "Our hearts are broken today."
It was the worst US massacre since the 2007 rampage at Virginia Tech university, and the latest in a deadly year. Just three days ago, three died after a gunman opened fire inside a mall in suburban Portland, Oregon. In August, a shooter took the lives of six people at a Sikh temple in Oak Creek, Wisconsin, before being killed by a police officer. In July, a masked gunman opened fire at a midnight movie in Aurora, Colorado, killing 12 and injuring 58.
Yesterday, it was Newtown's turn.
Shortly after 9:30 a.m., police received a call from the school, where students from kindergarten through fourth grade attend, Lieutenant Paul Vance of the Connecticut State Police said in a news briefing. The shooting took place in two rooms, he said.
The killer wore combat gear, CNN reported.
C.J. Hoekenga, a Sandy Hook fourth-grader, was in music class watching "The Nutcracker" when he heard bangs, heavy breathing and then shots. His teacher told them to get into a closet, the youngster said.
"At first I thought it was practice," C.J. said. "Then we realized it wasn't."
He and classmates said prayers until a police officer arrived. They then exited single-file and ran to a nearby fire station, he said.
"I'm relieved that most of the children got out and the man behind this is dead," C.J. said.
Ten-year-old Elise Beier, also a fourth-grader, said she could hear the gunfire and shouting over the public address system, which remained on throughout the incident.
Many killings took place in a kindergarten class, the Hartford Courant reported.
Automatic telephone calls alerted parents. Janet Ziperstein, 39, raced to the school to find her fourth- and second-grader unharmed.
"It was an eerie, odd, cold chaos," she said.
The bodies will remain where they fell until they are identified, Vance said. Parents haven't been allowed into the school to see their children, he said.
Authorities recovered two 9 mm handguns at the school, one Glock and one Sig Sauer, said a federal law-enforcement official who requested anonymity because the investigation was continuing. A .223-caliber rifle was also found, AP reported.
Lanza killed his mother at their home before driving in her car to the school, AP reported, citing a law-enforcement official briefed on the investigation and not authorized to discuss it.
Nancy J. Lanza and Peter J. Lanza were divorced in 2009, court records show.
Louise Tambascio, 70, a friend of Nancy's and owner of My Place, a restaurant where the suspect's brother used to work, said Adam Lanza had Asperger's syndrome. AP reported, citing a law-enforcement official briefed on the investigation, that he had a personality disorder.
Lanza was intelligent, but quiet and awkward, Tambascio said.
Mark Tambascio, her 45-year-old son, said Lanza was introverted.
"He couldn't deal with regular people," Mark Tambascio said. "He was kind of a sociopath."
Catherine Urso, a Newtown resident and piano teacher, said her son Nicholas went to Newtown High School with Adam Lanza. She said she used to see Adam dressed in Gothic garb.
Lanza's brother, 24-year-old Ryan Lanza of Hoboken, New Jersey, was questioned by police, AP said. He told officers he hadn't been in touch with his brother since about 2010, the news service said.
A huddle of officers and detectives escorted a man with a black jacket covering his head out of the Hoboken Police Department about 8:50 p.m. The man left in a white car with three others.
In Newtown, Nick Germak lives about two blocks from the Lanzas in a hillside neighborhood. Many residents are transient, moving to the area to take corporate jobs before moving to follow the next one, he said.
At least one neighborhood child, a boy in kindergarten or first grade with blond hair, was killed, Germak said.
"We moved to this remote town in New England and never expected this to happen," Germak said. "How do we put our kids on a school bus again and believe they'll be safe?"
As residents mourned, businesses in Sandy Hook's town square, including Sandy Hook Hair Co. and the Toy Tree, shut their doors early. Residents filed into Mass at St. Rose of Lima Church, a 3,500-member parish, said Brian Wallace, a spokesman for the Bridgeport diocese.
"This is a small town, very knit together and everyone knows everyone," he said. "We're here to pray with them and guide them through."
The deadliest shooting in the US in recent years is the Virginia Tech campus rampage of 2007, in which Seung-Hui Cho took 33 lives, including his own. In 1999, two students shot 12 classmates and a teacher in Columbine High School in suburban Denver before killing themselves.
The victims in Newtown were younger.
"The majority of those who died today were children, beautiful, little kids between the ages of 5 and 10 years old," Obama said. "They had their entire lives ahead of them, birthdays, graduations, weddings, kids of their own."