First-grade teacher Kaitlin Roig heard what sounded like the rapid firing of an assault rifle.
She herded her students into a bathroom. She helped some climb onto a toilet so they could all fit in the tiny room. Then she locked the door.
"I just told them we have to be absolutely quiet," she said.
As the minutes ticked by, the children asked Roig if she could "go see if anyone is out there."
No, she told them.
"If they started crying, I would take their face and tell them, 'It's going to be OK.' I wanted that to be the last thing they heard, not the gunfire in the hall."
Abbey Clements tried to keep calm for the sake of her students, she said. But she couldn't hide her fear.
"Mrs. Clements," they said. "You are shaking."
She wanted quiet so she could hear any instructions that might come over the loudspeaker system. But she also wanted to shout to drown out the constant sounds of gunfire, to shield little ears.
In a nearby classroom, Alexis Wasik, 8, began putting it all together when she heard the sirens outside. There had been a shooting at the school. Alexis and her classmates huddled together in the back of their classroom. Children were crying. Some were screaming.
Not everyone could see what was happening. But they could hear.
Chaos. Pandemonium. Horror.
After Lanza forced his way into the school, he shot Hochsprung and Sherlach when they stepped into the hallway.
Then he unleashed a hail of bullets inside two classrooms. In one was Lauren Rousseau, a substitute teacher who was filling in for a teacher out on maternity leave.
Lanza systematically shot everyone inside.
"There were 14 coats hanging there and 14 bodies. He killed them all," a law enforcement officer told the Hartford Courant.
The other classroom Lanza entered was Soto's. Her students were huddled behind her when Lanza burst in. He didn't say a word. He just pointed his rifle and sprayed the room with bullets.
A place that had been sanctuary was turned into hell.
For some, relief
Within 20 minutes, an army of police and emergency responders descended on Sandy Hook Elementary.
Lanza was in Soto's classroom when he heard the police closing in, officials believe. He shot himself with one of his hand guns.
Police marched the surviving students out of the school according to protocol for evacuating children. They asked them to put their hands on the shoulders of the kid in front of them, connected to each other like the cars of a train. They were told to close their eyes and walk out single file to a nearby firehouse.
Some stumbled past bullets and bodies. Then they ran to the firehouse. In tears. In shock.
By then, word of the shooting had spread. Parents rushed to the school, scrambled frantically to find their children.
"It was terrifying," said Brendan's father, Sean Murray.