The state's chief medical examiner, H. Wayne Carver II, said all of the 20 children and six adults gunned down at Sandy Hook Elementary School in Newtown, Conn., had been struck more than once in the fusillade.
He said their wounds were "all over, all over."
"This is a very devastating set of injuries," he said at a briefing in Newtown. When he was asked if they had suffered after they were hit, he said, "Not for very long."
The disclosures came as the police released the victims' names. They ranged in age from 6 to 56.
The children - 12 girls and eight boys - were all first-graders. One little girl had just turned 7 on Tuesday. All of the adults were women.
The White House announced that President Barack Obama would visit Newtown on Sunday evening to meet with victims' families and speak at an interfaith vigil.
On Saturday, as families began to claim the bodies of lost loved ones, some sought privacy. Others spoke out. Robbie Parker, whose 6-year-old daughter, Emilie, was among the dead, choked back tears as he described her as "bright, creative and very loving."
But, he added, "as we move on from what happened here, what happened to so many people, let us not let it turn into something that defines us."
On a day of anguish and mourning, other details emerged about how but not why the devastating attack had happened, turning a place where children were supposed to be safe into a national symbol of heartbreak and horror.
The Newtown school superintendent said the principal and the school psychologist had been shot as they tried to tackle the gunman in order to protect their students.
That was just one act of bravery during the maelstrom. There were others, said the superintendent, Janet Robinson. She said one teacher had helped children escape through a window. Another shoved students into a room with a kiln and held them there until the danger had passed.
It was not enough: First responders described a scene of carnage in the two classrooms where the children were killed, with no movement and no one left to save, everything perfectly still.
The gunman, identified as Adam Lanza, 20, had grown up in Newtown and had an uncle who had been a police officer in New Hampshire. The uncle, James M. Champion, issued a statement expressing "heartfelt sorrow," adding that the family was struggling "to comprehend the tremendous loss we all share."
A spokesman for the Connecticut State Police, Lt. J. Paul Vance, said investigators continued to press for information about Lanza, and had collected "some very good evidence." He also said that the one survivor of the killings, a woman who was shot and wounded at the school, would be "instrumental" in piecing together what had happened.
But it was unclear why Lanza had gone on the attack. A law enforcement official said investigators had not found a suicide note or messages that spoke to the planning of such a deadly attack. And Robinson said they had found no connection between Lanza's mother and the school, in contrast to accounts from authorities on Friday that said she had worked there.
Carver said it appeared that all of the children had been killed by a "long rifle" that Adam Lanza was carrying; a .223 Bushmaster semi-automatic rifle was one of the several weapons police found in the school. The other guns were semi-automatic pistols, including a 10 mm Glock and a 9 mm Sig Sauer.
The bullets Lanza used were "designed in such a fashion the energy is deposited in the tissue so the bullet stays in," resulting in deep damage, Carver said.
As to how many bullets Lanza had fired, Carver said he did not have an exact count. "There were lots of them," he said.
Carver said that parents had identified their children from photographs to spare them from seeing the gruesome results of the rampage. He said that four doctors and 10 technicians had done the autopsies and that he had personally performed seven, all on first-graders.
"This is probably the worst I have seen or the worst that I know of any of my colleagues having seen," said Carver, who is 60 and has been Connecticut's chief medical examiner since 1989.
He said that only Lanza and his first victim - his mother, Nancy Lanza - remained to be autopsied. He said he would do those postmortems Sunday.
Officials said the killing spree began early Friday at the house where the Lanzas lived. There, Adam Lanza shot his mother in the face, making her his first victim, the authorities said. Then, after taking three guns that belonged to her, they said, he climbed into her car for the short drive to the school.
Outfitted in combat gear, Lanza shot his way in, defeating a security system requiring visitors to be buzzed in. This contradicted earlier reports that he had been recognized and allowed to enter the one-story building. "He was not voluntarily let into the school at all," Vance said. "He forced his way in."
The lieutenant's account was consistent with recordings of police dispatchers who answered call after call from adults at the school. "The front glass has been broken," one dispatcher cautioned officers who were rushing there, repeating on the police radio what a 911 caller had said on the phone. "They are unsure why."
The dispatchers kept up a running account of the drama at the school. "The individual I have on the phone indicates continuing to hear what he believes to be gunfire," one dispatcher said.
Soon, another dispatcher reported that the "shooting appears to have stopped," and the conversation on the official radios turned to making sure that help was available - enough help.
"What is the number of ambulances you will require?" a dispatcher asked.
The answer hinted at the unthinkable scope of the tragedy: "They are not giving us a number."
Another radio transmission, apparently from someone at the school, underlined the desperation: "You might want to see if the surrounding towns can send EMS personnel. We're running out real quick, real fast."
Inside the school, teachers and school staff members had scrambled to move children to safety as the massacre began. Maryann Jacob, a library clerk, said she initially herded students behind a bookcase against a wall "where they can't be seen." She said that spot had been chosen in practice drills for school lockdowns, but on Friday, she had to move the pupils to a storage room "because we discovered one of our doors didn't lock."
Jacob said the storage room had crayons and paper that they tore up for the children to colour while they waited. "They were asking what was going on," she said. "We said: 'We don't know. Our job is just to be quiet."' But she said that she did know, because she had called the school office and learned that the school was under siege.
It was eerily silent in the school when police officers rushed in with their rifles drawn. There were the dead or dying in one section of the building, while elsewhere, those who had eluded the bullets were under orders from their teachers to remain quiet in their hiding places.
The officers discovered still more carnage: After gunning down the children and the school employees, the authorities said, Lanza had killed himself.
The principal, Dawn Hochsprung, 47, and the psychologist, Mary Sherlach, 56, were among the dead, as were teachers Rachel Davino, 29, Anne Marie Murphy, 52, Victoria Soto, 27. Lauren Rousseau, 30, had started as a full-time teacher in September after years of working as a substitute. "It was the best year of her life," The News-Times quoted her mother, Teresa, a copy editor at the newspaper, as saying.
Soto reportedly shooed her first graders into closets and cabinets when she heard the first shots, and then, by some accounts, told the gunman the youngsters were in the gym. Her cousin, James Willsie, told ABC News that she had "put herself between the gunman and the kids."
"She lost her life protecting those little ones," he said.
School officials have said that there are no plans to reopen Sandy Hook; its students will be assigned to other schools and return on Wednesday.
Among the victims was Ana Marquez-Greene, the 6-year-old daughter of jazz saxophonist Jimmy Greene, who moved to Newtown in July. He posted a comment on Facebook thanking several jazz musicians who had expressed condolences.
"As much as she's needed here and missed by her mother, brother and me," he wrote, "Ana beat us all to paradise." He added, "I love you, sweetie girl."
Dorothy Werden, 49, lives across the street from Christopher and Lynn McDonnell, who lost their daughter Grace, 7, in the rampage. Werden remembered seeing Grace get on a bus Friday morning, as she did every morning at 8:45. Shortly afterward, she received a call that there had been a lockdown at the school - something that happens periodically, she said, because there is a prison nearby. It was only when she saw police cars from out of town speed past her that she knew something was seriously wrong.
Like the rest of the nation, she said, local residents were struggling with a single question: Why?
"Why did he have to go to the elementary school and kill all of those defenseless children?" Werden asked.
(Reporting was contributed by Matt Flegenheimer, Thomas Kaplan and Ray Rivera from Connecticut; Joseph Goldstein, N.R. Kleinfield, William K. Rashbaum, Marc Santora, Michael Schwirtz and Wendy Ruderman from New York; and Michael S. Schmidt from Washington.)