The US school gunman used an assault rifle to pump his mostly six- and seven-year old victims with multiple bullets, authorities said Saturday, as details of the horrific spree became clearer.
Previously it had been reported that Adam Lanza (20) used two law enforcement style handguns to murder the 20 children and six adults at Sandy Hook Elementary School in Newtown.
But, as detectives continued to go over the blood-soaked school in the quiet town, authorities for the first time revealed that the principal weapon was a Bushmaster .233 rifle, which is designed for shooting people in military assaults.
"All of the wounds I know of at this point were caused by the long weapon," Connecticut's chief medical examiner, H. Wayne Carver told a news conference, referring to the semi-automatic, military grade rifle.
He also said that the majority of victims were "first graders wearing cute kids' stuff" and that all seven of the bodies he personally examined had been hit between three and 11 times.
Carver indicated that the rifle is a killing machine firing "bullets (that) are designed in such a fashion that the energy is deposited in the tissue, so the bullet stays in."
Connecticut State Police, meanwhile, released the ages of the victims, who included 16 six-year-olds and four seven-year-olds.
Twelve of the 20 slain children were girls and eight were boys.
The six adults killed were all women, including the school principal and the school psychologist, who at 56 was the eldest victim.
The information went a long way to filling in gaps in the picture of what happened in the massacre early Friday, just after classes started, and reaffirmed how well prepared Lanza was.
The motives of the shooter were the biggest mystery. Carver said that on Sunday he would conduct a post-mortem on Lanza and on his mother, who was shot in her home apparently just before Lanza went to the school.
Connecticut State Police spokesman Lieutenant Paul Vance said detectives had begun to "peel back the onion."
Asked whether any suicide note, emails or other clues to the killer's mind had been found, he said the crime scene "did produce some very - very good evidence in our investigation."
"Investigators will be able to use (this) in hopefully painting the complete picture as to how and more importantly why this occurred," he told a news conference.
Vance said the crime scene investigation could go on for 24 to 48 hours.
Bodies were removed from the blood-soaked school overnight on Saturday and relatives were privately given formal identification of the dead.
The small town was still struggling to come to grips with the sudden and overwhelming horror.
Although he was remembered as a shy, awkward and nerdy boy, Lanza had not apparently given any warning sign that he was a mass murderer.
The weapons, news reports said, were registered in his mother's name, but she was widely seen as an unremarkable and upstanding resident in the town.
It appeared that after gunning down his mother, Lanza, who was wearing black clothes, went to the school and concentrated his fire on just two rooms.
A new security system had recently been installed, but Vance said the shooter forced his way in to the school.
Police then entered from several points, breaking "many windows" as they frantically tried to get survivors out and to locate the gunman.
Mary Ann Jacob, who works in the school library, told reporters Saturday that she had sheltered 18 children during the mayhem.
"We were locked in our room," she said. "It was hard to keep them quiet. We told them it was a joke. I think they didn't really know what was going on."
The tragedy drew messages of support from around the world.
At a vigil late Friday, a Roman Catholic priest read out of a message from Pope Benedict XVI, conveying "his heartfelt grief and the assurance of his closeness in prayer to the victims and their families."
Britain's Queen Elizabeth II sent a message to US President Barack Obama in which she said she was "deeply shocked and saddened" and French President Francois Hollande expressed his condolences, saying the news "horrified me."
Obama, wiping away tears and struggling to maintain his composure, said on Friday he was aghast over the tragedy.
Of all US campus shootings, the toll was second only to the 32 murders in the 2007 massacre at Virginia Tech university.
The latest number far exceeded the 15 killed in the 1999 Columbine High School massacre, which triggered a fierce but inconclusive debate about the United States' relaxed gun control laws.
However, the White House on Friday scotched any suggestion that the politically explosive subject would be quickly reopened.