The gunman in the Connecticut shooting rampage shot his mother four times in the head before going to an elementary school and gunning down 26 people, authorities said as details emerged suggesting that Adam Lanza planned an even more gruesome massacre but was stopped short.
Lanza blasted his way into the school building and used a high-power rifle to kill 20 children and six adults, including the principal and school psychologist who tried to stop him, authorities said.
The unthinkable bloodshed might have been even worse. Connecticut Governor Dannel Malloy said Lanza shot himself after about 10 minutes of shooting as first responders entered the building, and a law enforcement official said Lanza had "lots of ammo" on him when he died, enough to carry out significant additional carnage.
"We surmise that it was during the second classroom episode that he heard responders coming and apparently at that, decided to take his own life," Malloy told ABC.
As President Barack Obama prepared to visit and churches opened their doors to comfort a grieving town, federal agents fanned out to dozens of gun stores and shooting ranges across Connecticut, chasing leads they hoped would cast light on Lanza's life.
Among the questions: Why did his mother, a well-to-do suburban divorcee, keep a cache of high-power weapons in the house? What experience did Lanza have with those guns? And, above all, what set him on a path to shoot and kill 20 children, along with the adults who tried to stop him? Malloy offered no possible motive for the shooting and a law enforcement official said police had found no letters or diaries left behind that could shed light on it.
Lanza shot his mother, Nancy Lanza, to death at the home they shared on Friday. She was shot four times in the head and found in bed wearing pyjamas, said a state official.
Lanza then drove to Sandy Hook Elementary School in his mother's car with at least three of her guns, forced his way in by breaking a window and opened fire, authorities said. Within minutes, he killed the children, six adults and himself.
All the victims at the school were shot with a rifle, at least some of them up close, and all were apparently shot more than once, Chief Medical Examiner Dr H Wayne Carver said. There were as many as 11 shots on the bodies he examined. Lanza died of a gunshot wound to the head from a 10 mm gun, and the bullet was recovered in a classroom wall. A Glock 10 mm handgun was among three guns found in the school.
Police later revealed that multiple 30-round magazines and hundreds of bullets were found at the scene of the school shooting.