A novice security guard who survived the shooting rampage last week at Red Lake high, Minnesota, described a frenzied scramble to protect students, and credited a fellow guard with saving lives by sacrificing his own.
In an interview with the Associated Press, LeeAnn Grant said security guard Derrick Brun, 28, ignored her pleas to run and rose from his desk to confront teenage gunman Jeff Weise.
"Derrick saved my life," said Ms Grant, 20. "He bought me time by confronting Jeff - for me to get that much further away with the students.
"Derrick's my hero. He didn't even look scared - he knew what he was going to do."
Ms Grant said she and Mr Brun had, as usual, been working at the doors of Red Lake high on Monday. Three of the four doors were locked while the open door funnelled pupils through a metal detector.
She described Weise stepping out of his grandfather's police truck - which the teenager had taken after killing both his grandfather and the old man's companion - and sending two shotgun blasts into the air.
Just four years older than Weise, Ms Grant had known the teenager for years and recognised the 6ft-tall, 18-stone student at once. As his black trenchcoat billowed, more guns were visible on the boy's belt.
Ms Grant, a mother-of-two, was unarmed and was not wearing a bullet-proof vest. She has only worked as a security guard since last August.
Outside the building, the gunman tried one door after another.
"He looked right at me. I made eye contact with him," she said.
Then the teenager found the unlocked door.
"He walked in and fired another shot, and I was telling Derrick, 'Come on - let's go. Let's go, Derrick. Run. We need to save these kids - we need to do something.'
"And I radioed in... 'There's a guy coming in the school and he's shooting and he has a gun.'
"Derrick just sat there at his desk... He just kept staring at Jeff. I kept hollering for him to come with me. He wouldn't come. He just stayed there."
The noise drew pupils towards the front doors. Some thought there was a fight and they wanted to see, Ms Grant explained.
"I started yelling at them, 'Run - there's a guy with a gun here! Just run!' And then I took off to try to protect them," she said.
"I turned back a little bit, and you could see Derrick kind of getting up, going right toward Jeff. And then I heard two shots again."
Other eyewitness accounts suggest that it was at that point that Mr Brun was killed. "I just ran," Ms Grant said.
But there was no refuge. Alerted to trouble, staff had locked the classroom doors in line with the school's crisis-response plan.
Ms Grant tried to open doors in a bid to find a place to hide while other pupils did the same. But none opened - and she had left her keys back at the front door.
Ms Grant said: "I told them, 'Never stop running - don't look back, no matter what.'"
Bullets hit the wall as Ms Grant also ran. A boy running a little ahead of her fell.
She added: "He got shot and went down, and then I was going to stop and grab him, but all those other students stopped and I told them to run.
"And then, by that time, Jeff was pretty much right by us again and I just ducked and took off again."
The gunman eventually turned down another hall, and Ms Grant and the students made it to safety outside the building.