SANTA FE, Texas — Yolanda Cadriel had thought it was a normal drill when the fire alarm went off in her first-period class at Santa Fe High School on Friday morning, and she and others filed out — until a teacher ran up and told her and her classmates to run.

She and the other students who had been waiting on school grounds for the principal to call them back to class took off running and sought shelter behind Indian Automotive across the street.

The narrow strip of space behind the windowless building where state vehicle inspections and repairs are done became the barrier between students and the carnage taking place in their school.

"A teacher that I know, he ran up to us and told us to run across the highway and we went to Indian Automotive. I never heard the shots, I didn't know what was happening," said Cadriel, 18, a senior. "They told us to hide behind the buildings and cars."

Even as a gunman opened fire, Santa Fe High School teachers and staff pushed, guided or directed students to safety, sending them to any shield of protection they could find, witnesses said.

Stories trickled out Saturday in the southeast Texas town near Houston about how this community looked out for its own, stories that mixed gratitude with heartbreak as official confirmation came of the names of the two teachers and eight students who were killed.

"I was confused, but I trusted him to tell us what we needed to do," Cadriel said of her teacher.

Authorities said Dimitrios Pagourtzis, 17, armed with a shotgun and .38-caliber pistol, opened fire at the school sometime before calls of an active shooter came in to police at around 7:32 a.m. local time Friday (8:32 a.m. ET).

Pagourtzis exited an art lab classrooms at around 8:02 a.m. and surrendered and later admitted to police that he shot multiple people inside the school with the intention of killing them, police said in court documents. He is charged with capital murder and aggravated assault against a public servant, and is being held without bond.

Cristina Surber, the mother of a freshman at Santa Fe, said her daughter was in theater class. Surber said her daughter told her that her class heard the fire alarm, but also heard what sounded like shots. Before releasing students, the teacher checked whether it was actually a fire drill, but was told it was a shooting, Surber said.

"The teacher took the students to a room with steel doors called shop," Surber said. "She [her daughter] texted me and told me she was OK."

Mehran Ali had arrived at the convenience store and gas station he manages just down the street from the high school at around 6 a.m. on the morning of the shooting. A former Houston school district teacher, he regularly sees teachers and students come in and out of the store.

Suddenly a girl who was crying came running into the store, "then after a little bit you see our whole parking lot full of students, faculty and parents," Ali said.

The store "was packed at one point," Ali said. “We didn’t mind ... We wanted everybody to be safe," he said.

Because they'd left all their belongings at the school, including cell phones, Ali said he allowed the students and staff to use their phone to call loved ones and check in as safe, and gave away water, soda and other goods.