The student had been shot twice, but Katie Holt had only one gunshot wound kit.
Holt, a choir teacher, was huddled with 30 to 40 students, hiding from a gunman who police said killed two people and wounded three others on Thursday morning at Saugus High School in Santa Clarita, about 35 miles north of Los Angeles.
One of the students who had run into the room with her told Holt that she believed she had been shot.
"I investigated with my phone flashlight, and yes, she had been shot," Holt said. So Holt left the locked office amid the chaos to retrieve her first aid bag and a gunshot wound kit. In today's world of school gun violence, such kits are increasingly common on campuses across the country.
"She was shot in her side, and then she told me she thought she had been shot, as well, in her arm," Holt said. "I looked, and she had been shot in her shoulder, as well — but I only had one gunshot wound kit."
Holt said she used what she had on the girl's shoulder wound and asked a "really brave freshman" named Tyler to apply pressure while she dealt with the other wound.
After they dressed both wounds the best they could, Holt said, they calmly called the police.
Holt said she heard from the girl's family and friends that she was out of surgery and would be all right.
Throughout the ordeal, the girl had been "really strong," Holt said. "She was even joking with me. She said, 'I'm going to be home-schooled after this.'
"All my students were really strong, because they were — obviously, they'll never be the same," she said.
Holt said she was relieved to hear that the student was all right. But, she said, "I don't think I should have had to process this. I don't think my kids, especially, should have to process this."
"Long term, I hope that something can be done, because I think that a really big change needs to happen," she said. "I held a bleeding child today in my classroom, in my music classroom."
Malena Peters, a student at Saugus, said that as she was being driven to school on Thursday morning, "we just see all these kids running and screaming."
Malena said her brother and two of her cousins were on campus when the shooting started, and "I was, like, freaking out."
"I was crying, because I didn't know if they were OK or not. I didn't know if they were hurt," she said. Eventually, they were all accounted for safely.
Just a couple of weeks ago, Malena and her friends had been talking about what they'd do if someone opened fire at their school.
"I never thought it would actually happen, you know?" she said.
Dionicio Flores, 17, a senior at Saugus, said that when he and his friends heard the first shot, "we kind of thought it was a milk carton being stepped on, because that happens pretty often."
But then, "we heard multiple shots in order, and we kind of, like — we didn't really say anything to react, we just ran towards the hill and escaped as fast as possible," he said.
Like many others, Dionicio said he "didn't expect it to happen."
"It just seemed like that kind of school — 'I don't think anyone's going to do that. It seems kind of a good school to go to."
So in the Saugus High School community, "parents don't expect this," said former Rep. Katie Hill, who graduated from Saugus in 2004 and represented Santa Clarita and surrounding communities in Congress until earlier this month.
"But I think it's becoming more and more the norm," Hill said. "And it's horrifying for us."
"Unfortunately, we're at a point where, as a public ... we talked all the time about how this is one of the worst nightmares to be happening in your community," she said.
"Not only for, of course, the tragedy," she said, "but because there's so little that you can say when you go back about what we can do."