The students inside a barricaded choir classroom were huddled in the dark minutes after shots rang out at Saugus High School in Southern California on Thursday, when one them said: "I think I got shot."

Katie Holt, a fine arts teacher, had pushed the piano in the music room against the classroom door, two students in the room told Reuters afterward, and grabbed a fire extinguisher, presumably to use as a weapon.

"She turned off the lights... She locked all the doors. She pushed the piano to the door, totally barricading," said Eddie Mendoza, 17 in a phone interview, his voice still breaking from emotion and grief.

At 7.38 am, a high school student on his 16th birthday, whose name has not been released, opened fire outside Saugus High School in Santa Clarita, killing a 16-year-old girl and a 14-year-old boy and wounding three other teens before shooting himself in the head, officials said.

California school shooting
A law enforcement official leads students at the scene of a shooting at Saugus high school in Santa Clarita, California, US, November 14, 2019 in this screenshot taken from video footage courtesy of NBCLA.Reuters

Students outside fled in panic, while those inside ran to safety in classrooms, as they had been repeatedly drilled to do.

One of them was one of the gunman's victims, Mendoza said.

"I think I'm bleeding. I think I got shot," he recalled her saying. "It was just so hard hearing her say 'I want my mom,' it was heartbreaking," Mendoza said.

'CALM AND COLLECTED'

Another student who identified herself only as Pamela said Holt retrieved a first aid kit that was in the classroom and began treating the girl's wounds on her shoulder and torso.

"Our teacher was very calm and collected," Pamela said, adding that the students all remained calm. Even the wounded girl, who remained conscious and alert, kept talking and "making jokes to cope with it."

Mendoza said of the teacher was "literally a hero."

"We did our best, we called 911 four times, we told them where we were."

Pamela said roughly 35 students were holed up in Holt's small office adjacent to the music room for about 29 minutes before they heard police pounding on the barricaded choir room door.

About seven officers then ushered the students out of the inner office into the choir room, with the students ordered to keep their hands raised to their heads.

"We all put our hands up," Mendoza said, "everyone crying and shaking."

With the school on lockdown, they were told to sit on the choir risers, where they were kept for about two hours before being escorted out of the school, Pamela said.

Students were taken by school bus to a reunification point at Santa Clarita's Central Park to meet their parents.

Pamela said the ordeal left her feeling "numb," as she sought to console other classmates shaken by the events. "I just feel distant from it," she said.

Her father, standing beside her, said, "I'm sure it will hit you later."