A look at some of those who died:
Maura Schwartz, of Deptford, Gloucester County, turned on the broadcast news Friday for information about the shooting.
Then, the news broke: Her mother, Mary Sherlach, was among the victims.
Schwartz had received a phone call from her sister, Sherlach's other daughter, frantically telling them that there was a shooting at the school. But it wasn't until news reports began confirming victim information that they learned of the death.
"It was a really helpless feeling," Schwartz's husband, Eric, told the West Deptford Patch. "For about an hour, you try to say, 'They got it wrong, they got it wrong.' "
Maura and Eric Schwartz immediately drove to the Sherlach family home in Connecticut, Patch reported Saturday morning.
When the shots rang out, Mary Sherlach threw herself into the danger.
Janet Robinson, the superintendent of Newtown Public Schools, said Sherlach and the school's principal ran toward the shooter. They lost their own lives, rushing toward him.
Sherlach was close to retirement, according to news reports. She had worked at Sandy Hook since August 1994, according to an online school biography.
Sherlach studied psychology at the State University of New York College at Cortland and received master's and professional degrees from Southern Connecticut State University.
She had been married to her husband, Bill, for more than 30 years and enjoyed traveling, gardening, and reading, Sherlach wrote. She wrote that she loved her job and the students.
- Jonathan Lai
Quick to cheer up those in need of a smile, Emilie Parker never missed a chance to draw a picture or make a card.
Her father, Robbie Parker, fought back tears as he described the beautiful, blond, always-smiling girl who loved to try new things, except food.
Parker, one of the first parents to publicly talk about his loss, expressed no animosity for the gunman, even as he struggled to explain the death to his two other children, ages 3 and 4. He's sustained by the fact that the world is better for having had Emilie in it.
"I'm so blessed to be her dad," he said.
She beams in snapshots. Her enthusiasm and cheer was evident. She was doing, those who knew her say, what she loved.
And now, Victoria Soto is being called a hero.
Though details of the teacher's death remained fuzzy, her name has been invoked again and again as a portrait of selflessness and humanity among unfathomable evil.
Investigators informed relatives that she was killed while shielding her first graders from danger. She reportedly hid some students in a bathroom or closet, ensuring they were safe, a cousin, Jim Wiltsie, told ABC News.
"She was trying to shield, get her children into a closet and protect them from harm," Wiltsie told ABC. "And by doing that, put herself between the gunman and the children."
Photos of Soto show her always with a wide smile, in pictures of her at her college graduation and in mundane daily life. She looks so young, barely an adult herself. Her goal was simply to be a teacher.
"She lost her life doing what she loved," Wiltsie said.
A year ago, Ana Marquez-Greene was reveling in holiday celebrations with her extended family on her first trip to Puerto Rico. This year will be heartbreakingly different.
The girl's grandmother, Elba Marquez, said the child's family moved to Connecticut just two months ago, drawn from Canada, in part, by Sandy Hook's pristine reputation. The grandmother's brother, Jorge Marquez, is mayor of a Puerto Rican town and said the child's 9-year-old brother was also at the school, but he escaped safely.
Elba Marquez had just visited the new home over Thanksgiving and finds herself perplexed by what happened.
"It was a beautiful place, just beautiful," she said. "What happened does not match up with the place where they live."
Jorge Marquez confirmed the girl's father is saxophonist Jimmy Greene, who wrote on Facebook that he was trying to "work through this nightmare."
"As much as she's needed here and missed by her mother, brother and me, Ana beat us all to paradise. I love you sweetie girl," he wrote.
Dawn Hochsprung's pride in Sandy Hook Elementary was clear. She regularly tweeted photos from her time as principal there, giving indelible glimpses of life at a place now known for tragedy. Just last week, it was an image of fourth graders rehearsing for their winter concert, days before that the tiny hands of kindergartners exchanging play money at their makeshift grocery store.
She viewed her school as a model, telling the Newtown Bee in 2010 that "I don't think you could find a more positive place to bring students to every day." She had worked to make Sandy Hook a place of safety, too, and in October, Hochsprung shared a picture of the school's evacuation drill with the message "Safety first."
When the unthinkable came, she was ready to defend. Officials said she died while lunging at the gunman in an attempt to overtake him.
"She had an extremely likable style about her," said Gerald Stomski, first selectman of Woodbury, where Hochsprung lived and had taught. "She was an extremely charismatic principal while she was here."
Lauren Rousseau had spent years working as a substitute teacher and doing other jobs. So she was thrilled when she finally realized her goal this fall to become a full-time teacher at Sandy Hook.
Her mother, Teresa Rousseau, a copy editor at the Danbury News-Times, released a statement Saturday that said state police told them just after midnight that she was among the victims.
"Lauren wanted to be a teacher from before she even went to kindergarten," she said. "We will miss her terribly and will take comfort knowing that she had achieved that dream."
Rousseau has been called gentle, spirited, and active. She had planned to see The Hobbit with her boyfriend Friday and had baked cupcakes for a party they were to attend afterward. She was born in Danbury, attended Danbury High, college at the University of Connecticut, and graduate school at the University of Bridgeport.
She was a lover of music, dance and theater.
"I'm used to having people die who are older," her mother said, "not the person whose room is up over the kitchen."
Chase Kowalski was always outside, playing in the backyard, riding his bicycle. Just last week, he was visiting neighbor Kevin Grimes, telling him about completing - and winning - his first mini-triathlon.
"You couldn't think of a better child," Grimes said.
Grimes' own five children all attended Sandy Hook, too. Cars lined up outside the Kowalskis' ranch home Saturday, and a state police car idled in the driveway. Grimes spoke of the boy only in the present tense.
Charlotte Bacon, 6
Daniel Barden, 7
Rachel Davino, 29
Olivia Engel, 6
Josephine Gay, 7
Ana Marquez-Greene, 6
Dylan Hockley, 6
Dawn Hochsprung, 47
Madeleine Hsu, 6
Catherine Hubbard, 6
Chase Kowalski, 7
Jesse Lewis, 6
James Mattioli, 6
Grace McDonnell, 7
Anne Marie Murphy, 52
Emilie Parker, 6
Jack Pinto, 6
Noah Pozner, 6
Caroline Previdi, 6
Jessica Rekos, 6
Avielle Richman, 6
Lauren Rousseau, 30
Mary Sherlach, 56
Victoria Soto, 27
Benjamin Wheeler, 6
Allison Wyatt, 6
SOURCE: Connecticut State Police