The Oregon school shooter went to extreme lengths to carry out his evil carnage and make his way to his target: his former special-needs classroom, law-enforcement sources told The Post on Friday.

Griffin J. John, 16, first threw his Maverick 88, a 12-gauge pump-action shotgun, over the fence at Silver Rail Elementary School in Bend around 1 p.m. Thursday and hopped over himself, sources said.

The gun-toting young madman then tried to enter through the school’s front door but was blocked by two bystanders, including a dad of two little girls at the school who noticed the property breach while driving by on his way home for lunch, sources said.

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Oregon school shooter Griffin J. John pictured in a photo posted by his mother, Shauntai Nickerson, on Facebook on Sept. 10, 2026. facebook/Shauntai NIckerson

Police seen stationed outside of the crime scene at Silver Rail Elementary on Oct. 16, 2026. AFP via Getty Images

The man opened fire on John with a concealed weapon he was carrying, thwarting the teen’s attempt to go in the front, sources said.

Refusing to give up, John ran around to the school’s back door and blew off its lock — which was designed to prevent such tragedies, sources said.

Rhoam Summer, 5, in an undated Facebook photo posted by his parents, Lillian and Kelik Summer, was shot and killed in a mass shooting at Silver Rail Elementary School in Bend, Oregon. Basic Beginnings / Facebook

He entered the school and headed straight for his former special-needs classroom and opened fire, killing three students, ages 5, 8 and 11, and a teacher, while also injuring a 7-year-old in a wheelchair and a 54-year-old teacher before being gunned down by the gun-toting dad who had spotted him out front.

John’s weapon had been legally purchased by his mother Shauntai Nickerson around the time of his August birthday, sources said.

Blood, obscured center, is seen on the ground outside of the Bend elementary school.. REUTERS

Nickerson was seen on the porch of her second-story home by reporters Friday smoking a cigarette and crying.

“I’m sorry … I miss him,” Nickerson reportedly said, adding that the suspected killer was “a good boy, he really was.”

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She did not discuss her purchase of the murder weapon but said, “If I could have prevented this, I would have.”

Mourners leaving flowers at a makeshift memorial at Silver Rail Elementary School on Oct. 16, 2026. REUTERS

John’s special-education history had been documented in a KTVZ report from 2020 that quoted his mother discussing his troubles with remote learning during the pandemic.

“I think it will be great for Griffin [to return to the classroom] because I am not certified teaching a special-needs student,” Nickerson told the outlet.