Candlelit vigils were held in Newtown, Connecticut, for the victims of gunman Adam Lanza, 20, who shot his way into the school armed with a powerful civilian version of a military rifle, a Sig Sauer rifle and a Glock handgun. His child victims were all aged six or seven, and they were shot up to 11 times each.
Lanza has been described as an odd-ball character who was devastated by the break-up of his parents' marriage.
His victims included six women, including Sandy Hook headteacher Dawn Hochsprung, 47. The killer's mother Nancy was also found dead from multiple gunshot wounds. Lanza had killed her before driving to the school, where as police closed in on him he took his own life by shooting himself in the head.
Friday's massacre, one of America's worst school shootings, brought despair and horror to the New England community, which is 60 miles north-east of New York City.
The names of the victims are likely to be used in the coming weeks, months and years by those wishing to rid America of the right of its citizens to bear arms.
Among the victims were Emilie Parker, Ana Marquez-Greene, British-born Dylan Hockley, Noah Pozner, Olivia Engel, Catherine Hubbard, who were all aged six and Grace McDonnell, seven.
In addition to Mrs Hochsprung, 47, who had recently told the town's newspaper there was no more positive place to bring students every day, several colleagues died, including Victoria Soto, 27, who tried to shield her pupils.
Mary Sherlach, 56, superintendent of Newtown Public Schools and a psychologist, was cut down by Lanza as she ran towards him with the headteacher. Also killed were teacher Lauren Russo, 30, and Anne Marie Murphy, 52. The body of Mrs Murphy, a mother of four, was found covering children she had shielded from Lanza.
Victims were hit multiple times and at least one was shot 11 times, authorities said.
"If this doesn't shake the consciousness of the country about doing better to protect our children, I don't know what will," said Pedro Segarra, mayor of Hartford, the state capital.
Robbie Parker, father of Emilie, who was studying Portugese with her father, said: "This world is a better place because she has been in it."
While townspeople grieved, investigators continued to examine forensic evidence and scour the crime scene in a process likely to last weeks.
Many more witnesses need to be interviewed, possibly including child survivors.
Lietenant Paul Vance of the Connecticut State Police said: "We have the best of the best working on this case. Our goal is to paint a complete picture so that we all know and the public knows exactly what happened here."
At a Mass at St Rose Catholic church, the priest said a Christmas pageant rehearsal would go ahead, minus one of the victims, Olivia Engel who was due to play an angel.
Members of the Jewish community also showed support for the survivors. About 30 members of the Islamic Association of Connecticut carried tulips to lay on the memorials in front of the church.
Makeshift memorials have appeared across the town. The largest, festooned with flowers and teddy bears, has been established at the end of Dickenson Drive, where Sandy Hook Elementary stands.
Residents and visitors yesterday streamed past a police roadblock to add to it. One woman knelt down and sobbed violently.
As the children walked down the street in the rain, carrying their toys and signs, a man sat on the back of his parked car playing a mournful tune on a violin to accompany them.