The brave dad who killed Oregon elementary school shooter Griffin John stalked the teen gunman and army crawled through a school window to stop him, the hero’s mother revealed.

Kaylub Giamaco, who has two daughters who attend Silver Rail Elementary School, was heading home from his lunch break when he heard gunshots and saw John, 16, entering the building.

Giamaco’s proud mom, Kenda Freeman, told CBS News that her son didn’t hesitate to jump into life-saving action to stop the maniac gunman from killing more helpless victims.

Kaylub and Kelsey Giamanco are seen in an undated Facebook photo. facebook/Kaylub Giamanco

Cops are still investigating Griffin J. John II’s motive for the shooting. facebook/Shauntai NIckerson

“Kaylub knew something was not right, so he pulled up onto the grass, grabbed his gun and basically stalked the gunman back into the school,” she told the outlet.

“He crawled through a window that the gunman had shot out. He army crawled through the window.”

Here’s the latest on the elementary school shooting in Oregon:

• Teacher, 25, killed by Oregon school shooter ID’d as volleyball coach Megan Lambert: ‘She lit up the room’
• Hero teacher tackled Oregon school shooter Griffin John – who was armed to the teeth in special ed classroom: police
• The extreme measures Oregon shooter took to enter the school — and why he targeted special-ed room
• First photos of Oregon school shooter Griffin John revealed

In a heart-pounding call to his mother immediately after, Giamaco said: “’Mom, I just shot and killed somebody. A man went into my daughters’ school and shot kids and I looked at him point-blank, and I shot and killed him, Mom.”

John killed three students — 5-year-old Rhoam Summer, an 8-year-old, and an 11-year-old — and teacher Megan Lambert, 25.