A survivor of the Michigan State University mass shooting recalled Tuesday how the killer didn’t say a word as he shot up her classroom — and how heroic students put their lives on the line to save others.

Claire Papoulias told the “Today” show that it had been a regular evening history class with about 20 students when she suddenly heard “three or four gunshots directly behind my head.”

“I dropped to the floor with all my classmates and someone was yelling that there was a shooter,” she said, with the gunman not saying anything.

“At that moment, I thought I was gonna die. I was so scared.”

Papoulias said gunman Anthony Dwayne McRae, 43, “came through the back and just started attacking people.”

“And I will never forget the screams of my classmates,” she said. “They were like screaming in pain [and] for help.”

Despite the deadly danger, some classmates “jumped into action, trying to help everyone,” Papoulias said, including some who raced to close doors and others who broke windows to allow others to escape.

“If it weren’t for my classmates helping everyone, I don’t think that we would have all made it,” she said, recalling how some helped guide others through the window.

“There was a boy in my class and he was waiting outside the window and he was catching people … so that they wouldn’t fall and couldn’t run away,” she said.

“And I’m so grateful that he was there to help people out,” she said, adding that once she was out, she “just ran for my life.”

During the carnage, she had called her mom, Natalie Papoulias, who “heard about three gunshots and screaming” on Claire’s end.

“It was my worst nightmare,” the mom told “Today,” saying she felt her legs would give way as she rushed to get in her car to race to the campus.

“I mean, I feel like she literally like dodged a bullet,” the relieved mom said.

The student said her boyfriend would usually have arrived at that time to pick her up, but skipped Monday because a friend was sick.

“I think if my boyfriend was there, he would’ve definitely gotten injured,” she said, calling it “a miracle that he was not there.”

Cops earlier Tuesday identified the killer as McRae, who previously served time behind bars after being busted with a loaded weapon.

He was found dead from a self-inflicted gunshot wound just over three hours after shooting up two areas of the campus, police said.

MSU Police Interim Deputy Chief Chris Rozman said early Tuesday that authorities have “absolutely no idea what the motive was” and that McRae “had no affiliation to the university.”

All three people killed were students, cops said, without identifying them. The five injured — also students — remained in critical condition Tuesday morning.