When Adam Lanza stormed into Victoria Soto's classroom, he was armed with a rifle and two semi-automatic pistols with which he had already killed 20 small children. She had only her courage, and her instinct to protect her class.
Soto, 27, was alone. A friend, posting on her Tumblr account, said: "When the shooting started Vicki hid her kids in closets and when the gunman came into her room she [said] the class was in gym."
That lie saved their lives, but it didn't save hers.
Lanza shot her dead and then, frustrated, turned the gun on himself.
Her cousin Jim Wiltsie told ABC News: "I'm just proud that Vicki had the instincts to protect her kids from harm. It brings peace to know that Vicki was doing what she loved, protecting the children, and in our eyes she's a hero."
She is not the only one.
If anybody wanted to know the kind of people who become teachers, they need only read of the bravery of the staff at Sandy Hook Elementary School.
It starts with the principal, Dawn Hochsprung, who had the presence of mind to turn on the school intercom, broadcasting screaming and gunshots into every classroom, so that others had time to take cover.
"That saved a lot of people," said teacher Theodore Varga, who survived the massacre.
Hochsprung was in a meeting with a parent and senior staff when Lanza began shooting nearby. At the sound of gunshots and screaming, some in her office dived for cover, but Hochsprung and the school's psychologist, Mary Sherlach, 56, ran out to confront Lanza, shouting back to the others to lock the door. They were both shot dead, Hochsprung as she lunged at the killer.
Sherlach was preparing to retire, having helped hundreds of students go through family break-ups, bullying and events that - until Saturday - had been the toughest moments of their young lives. While others hid, she and the principal ran towards the danger.
School therapist Diane Day, who was in the meeting, said: "They didn't think twice about confronting [him] or seeing what was going on."
Another teacher used her body to hold the door shut, and was shot in the leg and arm through the door.
Music teacher Maryrose Kristopik kept 20 children safe by barricading them into a closet. Even when the gunman battered on the door screaming, "Let me in! Let me in!" she kept her nerve and blocked the door with her body.
Kristopik said: "I talked with them to keep them quiet. I told them that I loved them. I said there was a bad person in the school. I didn't want to tell them anything past that.
"I was just trying to be as strong as possible. I was thinking about the children. I told them that we had to keep quiet and we were hiding and nobody knew we were there.
"Of course I was afraid too. I wanted them to be quiet, I thought it was a pretty secure, out-of-the-way place."
She led her children out only when she heard the gunshots had stopped.
Brenda Lebinski said her 8-year-old daughter was safe thanks to the teacher's actions. "My daughter's teacher is my hero," Lebinski said. "She locked all the kids in a closet and that saved their lives."
Large windows left teacher Kaitlin Roig's classroom exposed, so she huddled 15 children into a tiny bathroom when she heard gunshots. The 29-year-old locked the door and pulled a bookshelf across it. She said it was a struggle to get all the pupils in but she knew it was their only option.
"I put one of my students on top of the toilet. I just knew we had to get in there. I was just telling them they were going to be okay," she told ABC News. "I told them we had to be absolutely quiet because I was afraid that if he did come in and hear us he would just shoot at the door. I said there are bad guys out there now. We need to wait for the good guys."
Thinking these might be their last moments alive, she assumed the role of a parent. "I said, 'I need you to know that I love you all very much and it's going to be okay.' Because I thought we were all going to die. I wanted them to know someone loved them and I wanted that to be the last thing they heard."
When the police arrived to tell them it was safe to come out, Roig was so frightened she made them put their badges under the door so she could be sure it was them.
Another teacher, Abbey Clements, acted quickly to save lives. When she heard gunshots outside her classroom she initially thought they might be folding chairs, left out for a concert, falling over. But when she looked outside she was confronted with a very different scene.
"When I poked my head out the door and saw the custodian [janitor] running to the front of the building I realised they were shots," she said.
She pulled two students and two other teachers who were standing in the hall through her door to hide them. "We corralled those two kids into my classroom to stay with me. We went into lockdown, which meant that I ran to get the keys and told the kids to sit in the place where we practised for emergencies.
"It was even scary to lock the door because I had to open the door back up and put my hand out because the lock is on the outside and then come back into the closet area," Clements added.
Trying to calm the children, she attempted to muffle the haunting sounds of gunshots and screams broadcast over the intercom and read them stories.
An unidentified teacher saved an 8-year-old pupil. He was standing in a hallway as bullets whistled through when he was pulled from harm. "I saw some of the bullets going down the hall that I was right next to and then a teacher pulled me into her classroom," the boy told CBS News.
It was not just teachers who showed extraordinary courage. While the gunman roamed the halls, the school janitor ran along corridors shouting, "Guys! Get down! Hide!", checking that classroom doors were locked. And librarian Yvonne Cech locked herself, two library clerks, an assistant and 18 fourth-graders in a closet behind the library's filing cabinets while the sound of gunfire cracked outside.
What we know
The victims total 28, including the gunman, Adam Lanza; his mother, Nancy Lanza; the school's principal, Dawn Hochsprung; and 20 schoolchildren, all 6 and 7 years old. A woman who works at the school was wounded. The medical examiner said the victims were shot multiple times by a semi-automatic rifle. He said at least some were shot up close. All six adults killed at the school were women. Of the 20 children, eight were boys and 12 were girls.
Adam Lanza, aged 20, wore a pocket protector when he was a teen in school and was an honour student. He was called "remote" and "probably a genius" by classmates. Lanza had been diagnosed with Asperger's, a mild form of autism. People with Asperger's are often highly intelligent. There is no evidence of a link between Asperger's and violent behaviour, experts say. He grew up in an affluent neighbourhood. Investigators said they believed Lanza attended Sandy Hook Elementary many years ago. In high school, he was active in the technology club. The club adviser remembered that he had "some disabilities" and seemed not to feel physical pain like the other students. That meant Lanza required special supervision when using soldering tools, for instance. He also had an occasional "episode" in which he seemed to withdraw completely from his surroundings, the adviser said. Authorities said Lanza had no criminal history, and it was unclear whether he had a job. Police said he forced his way into the school by breaking a window and that investigators had found "very good evidence" they hoped would answer questions about a motive. But an official said investigators had found no note or manifesto.
Police told children to close their eyes as they led them from their classrooms past the carnage. The intercom broadcast screams; witnesses heard popping sounds, or, as a boy said, something that sounded like "cans falling". Crying children were escorted through the school's parking lot in line, hands on one another's shoulders, as panicked parents raced to the school. Witnesses said the shooter said nothing.
Where they died
Most of the dead were found in two classrooms; Lanza's mother, Nancy, was found dead at her home. The children killed were aged 6 and 7.
Lanza's mother was once a stockbroker in Boston. She was no longer working. She was well-liked and was called a nurturing parent who enjoyed hosting dice games and gardening. Reports on Saturday which said that she taught at the school were corrected yesterday to say she had no link. She divorced Peter Lanza, a tax director who lives in Stamford, Connecticut, four years ago. Lanza's 24-year-old brother, Ryan, works in Manhattan and was questioned by police near his New Jersey home but is not a suspect.
Idyllic, 300-year-old Newtown is a picture postcard New England town. The Spencer Tracy-Katharine Hepburn comedy Adam's Rib was filmed decades ago on a lake in the town, now a bedroom community of 27,000 from which executives commute to Manhattan.
The shooting is the second-deadliest in US history and one of the deadliest mass shootings around the world. A gunman at Virginia Tech University killed 33, including himself, in 2007. Only Virginia Tech and the mass killings of 77 in Norway in 2011 have had greater death tolls across the world over the past 20 years.
Read more: Snapshots of the gunman's victims