When the shots rang out, Vollmer locked her classroom door, covered the windows, including the one in the door, then took the children into a nook between bookcases and a wall.
She read them a story to keep them calm.
"They kept saying 'How come we're here for so long?' 'Well, it will be a little longer.' " she answered. "When they're 5, you do whatever you can to keep them safe and keep them calm."
"We're going to be safe," Vollmer told them, "because we're sitting over here and we're all together."
First-grade teacher Kristen Roig herded her students into a bathroom, locked the door and told them not to make a peep.
They got impatient, antsy, wanted someone to go out and see what was happening. No, she told them. She was afraid they would all die.
"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," she said, "not the gunfire in the hall."
The wait dragged on, Vollmer said.
"Maybe it was 20 minutes, a half-hour; I'm not sure."
Police knocked at the door to take them all out. They instructed her to have the schoolchildren hold hands and close their eyes.
"At 5, it's not so easy to close your eyes and walk," Vollmer said. "So I had them look toward the wall." They all had to be brave.
President Barack Obama eulogized the teachers in a speech to Newtown and the nation Sunday night.
"They responded as we all hope we might respond in such terrifying circumstances -- with courage and with love, giving their lives to protect the children in their care," he said.
"We know that there were other teachers who barricaded themselves inside classrooms, and kept steady through it all, and reassured their students by saying 'Wait for the good guys, they're coming'; 'Show me your smile.'"
Now Newtown will need to muster the courage to rebuild, to keep raising the siblings of fallen angels, to face another day without a beloved child.
Sandy Hook Elementary will probably move into another building, away from the scene of the spilled blood and bullet holes. Teachers and children will go back to class, prepare lessons, do homework, take tests and grade them.
"We need to get the kids back in school," Vollmer said.
Vollmer, her colleagues and the children have all seen and heard too much and gotten through it bravely. Even soldiers experience permanent trauma after seeing a child being killed -- let alone 20 at once.
The stories of how these teachers and school administrators risked their lives -- and in six instances gave them -- to protect their young students spurred CNN readers to label them heroes.
"The next time people criticize teachers, think of these heroes and know that any teacher would do the same for their students. Your children," wrote Tom in the online comment section below this story. "How many dozen lives were likely saved because the teachers and administrators knew what to do?"