The Oregon father hailed as a hero for stopping a school shooting last week spoke for the first time about the incident, describing his experience and how he told a 911 operator: “I have to go in. People are going to die.”

Kaylub Giamanco, a 36-year-old carpenter, has received national attention and praise for stopping the bloodshed at Silver Rail elementary in Bend, Oregon, where his children attend school.

He fatally shot Griffin J John II, a 16-year-old former student at the school, who broke in and shot six people, killing Megan Lambert, a 25-year-old teacher, and three children, including five-year-old Rhoam Summer.

In an interview with Oregon Public Broadcasting (OPB), his first since the 15 October shooting, he recounted that day. He told reporters that he was only in the area because he had decided to return home and eat lunch with his wife rather than the meal he brought to work that day.

For a moment, Giamanco, who lives near the school, thought it was a prank when he saw a man in black armed with a gun headed toward Silver Rail, he said. Then he saw the man fire the gun and climb over a school fence. Giamanco pulled out a .40 caliber handgun from his center console and headed into the school parking lot, calling 911, before himself hopping over a fence to pursue the shooter.

He quietly followed Griffin without the teenager seeing him, at one point crawling on his hands and knees when he heard “children pleading for their lives”.

“I just started army crawling faster and faster and I told myself this is probably the last thing that I’m ever going to do,” he told OPB.

Giamanco crawled through a broken window and toward the special education class Griffin had entered, where a teacher was fighting with the shooter. He came into the classroom and fired his gun. Griffin fell and was reaching for his weapon before Giamanco, who said he “was afraid of him shooting anybody else”, shot him two more times.

He told OPB that he lies awake at night thinking of what he saw that day and the teenage perpetrator, and wonders if he could have done more.

“I want to apologize for not saving their babies,” Giamanco told the outlet. “The gratitude for saving people’s children is awesome, but there were ones that I didn’t save.”

Giamanco said he wants to see safer schools with school resource officers at every site, and that he would like to raise funding to support school safety efforts.