Screams blared over the intercom and gunshots echoed in the halls at Sandy Hook Elementary School.
Eight-year-old Sofia Lebinski and 18 of her third-grade classmates huddled on the floor, in the corner farthest from the door, while her teacher hunched with them and an assistant hid behind a desk.
As soon as they heard the "boom" of gunshots, the aide locked the classroom door while the teacher called 911, Sofia recalled Friday.
"Everybody was shaking," the girl said, "because we didn't know what was going on, and everybody was all squished."
In another classroom, students hid in closets during the morning rampage that left 20 children and six adults dead in the K-4 school in rural Newtown, Conn.
They had practiced fire drills, but nothing prepared them for the terror of the shooting spree -- hearing scores of gunshots and the 20-year-old killer's curses.
Fourth-grade teacher Theodore Varga said the sounds that played over the intercom were a warning that saved many lives.
"You could hear people in the office," said Varga, who was in a teachers' meeting at the time. "You could hear the hysteria that was going on. I think whoever did that saved a lot of people. Everyone in the school was listening to the terror that was transpiring."
A custodian ran through the school, warning people of a gunman on the loose, Varga said.
"He said, 'Guys! Get down! Hide!' " the teacher said. "So he was actually a hero." Varga did not know if the custodian survived the attack.
For anxious minutes, youngsters and teachers were prisoners in classroom closets and corners.
Then came a knock on the door of Sofia's classroom. They feared it was the shooter, she recalled.
"Somebody said, 'You can come out now,' " Sofia said, "and we thought it was the guy, but the assistant teacher looked out the door, and there was the police."
Fourth-grader Brendan Murray, 9, was in the gym with his classmates when they heard "lots of banging."
Teachers hid the students in a nearby closet for about 15 minutes, the boy told the Hartford Courant, before police arrived and led them safely outside.
As students ran down a hallway, police stood at every doorway, Brendan said. "Lots of people were crying."
In the parking lot, Sofia's mother, Brenda Lebinski, was frantically asking people what had happened and looking for her daughter.
"One of my neighbors said there was a little girl taken out and she looked like she was dead, and I panicked," Lebinski, 47, said.
Then she saw Sofia with her teacher.
"She was a little confused, but she was OK. Her face was red. When she gets upset, her face turns red," Lebinski said. "I was so happy to see her -- so happy. Tears of joy."
The children and their families, along with school staff, were escorted to a nearby firehouse, where authorities conducted a roll call to see who was missing.
"There were a lot of kids screaming and crying, and teachers were devastated," said Lebinski, who volunteers Thursdays at the school.
People were trying to figure out who was alive and which of their children's friends didn't make it, she said.
"That's when I saw another mom, who told me she was there at the school. She said a masked gunman came in and started shooting and that the principal was dead. I said, 'The principal is dead? She was such a wonderful lady.'"
School district Superintendent David Fleishman told parents Friday that counseling would be available at the school starting Monday.
But Lebinski isn't sure if she wants to send her daughter back so fast.
"You send your baby off to the school, where she's supposed to be safe," the mother said. "I don't know what to do. I can't imagine sending her back there."