The victims of the US school shooting were shot multiple times by a semi-automatic rifle, the medical examiner said, as a clearer picture emerged of the deadly massacre that killed 20 children.
The names of the children have also been released. Among the victims were 12 girls, eight boys and six women.
Medical examiner Dr Wayne Carver said the attack at Sandy Hook Elementary School on Friday resulted in a 'devastating set of injuries'.
He said he examined seven of the 20 children killed, and two had been shot at close range. When asked how many bullets were fired, he replied, 'I'm lucky if I can tell you how many I found.'
Police said they had found 'very good evidence' which they hoped would answer questions about the motives of the 20-year-old gunman, described as brilliant but remote, who forced his way into the school and killed 26 children and adults in one of the world's worst mass shootings.
Witnesses said the gunman, Adam Lanza, didn't say a word as he shot children as young as five years old and later killed himself. Police, however, said on Saturday they had not officially identified the shooter. Reaction was swift and emotional around the world, as many immediately thought of Dunblane - a 1996 shooting in that small Scottish town which killed 16 small children and prompted a campaign that ultimately led to tighter gun controls.
Pressure to take similar action built on US President Barack Obama, whose comments on the tragedy were one of the most outwardly emotional moments of his presidency.
'The majority of those who died were children - beautiful little kids between the ages of five and 10 years old,' Obama told a White House news briefing, struggling to keep his composure. He promised 'meaningful action' on the issue of mass shootings, 'regardless of the politics'.
On Saturday, stunned residents and exhausted officials continued to fill in the details of the attack. The school's well-liked principal, Dawn Hochsprung, was killed while lunging at the gunman as she tried to overtake him, town officials said. Board of Education chairwoman Debbie Liedlien said administrators were coming out of a meeting when the gunman forced his way into the school, and they ran toward them.
Asked whether Hochsprung was a hero, the chairman of the town's Legislative Council, Jeff Capeci, said, 'From what we know, it's hard to classify her as anything else.'
In Newtown, a small and picturesque New England community 95 kilometres northeast of New York City, hundreds of people packed St Rose of Lima church on Friday night and stood outside in a vigil for the 28 dead - 20 children and six adults at the school, the gunman's mother at home, and the gunman himself.
Just one person, a woman who worked at the school, was shot and survived - an unusually small number in a mass shooting. Investigators had not found evidence after talking with state gun dealers and gun ranges that the gunman trained for the attack or was an active member of the recreational gun community, US Bureau of Alcohol, Tobacco and Firearms spokeswoman Ginger Colbrun said.
Lanza is believed to have suffered from a personality disorder and lived with his mother, said a law enforcement official who was briefed on the investigation.
Lanza shot his mother, Nancy Lanza, drove to the school in her car and shot up two classrooms on Friday morning, law enforcement officials said, speaking on condition of anonymity.
A custodian ran through the halls, warning of a gunman, and someone switched on the intercom, perhaps saving many lives by letting them hear the chaos in the school office, a teacher said. Teachers locked their doors and ordered children to huddle in a corner or hide in closets as shots echoed through the building.
Maryann Jacob, a clerk in the school library, was with 18 students when they heard gunfire outside the room. She had the children crawl into a storage room, and they locked the door and barricaded it with a file cabinet. There happened to be materials for colouring, 'so we set them up with paper and crayons'.
Kaitlin Roig, a teacher at the school, said she implored her students to be quiet.
'If they started crying, I would take their face and say it's going to be OK. Show me your smile,' she said. 'They said, 'We want to go home for Christmas,' 'I just want to hug my mum,' things like that, that were just heartbreaking.'