The quiet of small town Minnesota had been broken.

“Code Red! Code Red!” over and over, a 16-year-old Eric Decker heard. That vague, yet distinct alarm of panic blared through Rocori High School, as students and teachers and faculty scrambled and sprinted and screamed. There were sirens, and the unmistakable, unsettling sound of helicopters.

There’s no forgetting the moment — Decker in the cafeteria, David Sauer in biology class, James Herberg in the hallway — when the shots were fired.

On Sept. 24, 2003, 15-year-old John Jason McLaughlin walked into the gymnasium and killed senior Aaron Rollins and freshman Seth Bartell, before gym teacher Mark Johnson bravely approached the shooter with the gun pointed at him, raised his hand and shouted “No!” at McLaughlin, miraculously prompting him to drop the weapon and end the senseless slaughter.

Decker, who was friends with both victims, was with Seth’s brother Jesse when the shots rang out. Decker sprinted through the school and past the gymnasium, ending up in a dark library closet, where he stayed for roughly 45 minutes with other students, consumed by confusion and fear.

“For me, it’s taken years to get over, and even now I still have times where I either remember something or am in a certain situation and become a little scared because of that,” the Broncos wide receiver told The Post on Friday. “Friends, family, the community … that’s who I leaned on during that time. … We are such a small town, a town of 3,000 people, so it really brought everyone together … the camaraderie and that support system.”

Nothing seemed easy in the immediate aftermath, but Decker’s friends said knowing that no one was going through it alone made all the difference.

“At the time, we just handled it by sticking together, hanging out with our friends, and if we needed to talk about, we talked about it,” said Sauer, Decker’s high school quarterback, next-door neighbor and best friend growing up.

“It took time,” Herberg, Decker’s longtime friend and current teacher at Rocori, said with a deep breath and a long pause. “It never truly was the same, but I always tell people, I would never come back and live in a community if I didn’t think it was a great place to live in. We have a lot of pride, and I think we handled the situation the best that anyone could handle the situation.”

Decker had grown accustomed to the quiet, being raised in the small town of Cold Spring, Minn. — a town along a highway, in the shadow of St. Cloud and cloaked in the anonymity of flyover cities in the Midwest.

It is a conservative, rural town, where the farms outnumber traffic lights and fishing is favored at several of the state’s 10,000 or so lakes nearby. It is a place where everyone may not know everyone, but everyone knows someone who knows everyone.

“It’s a pretty tight-knit community, no question about it,” Herberg said. “People go out of their way to do things for each other and I think that makes it special and unique.”

Decker was the all-everything athlete and be-everyone person at Rocori High School. Popular, witty and funny, Decker is described with the likeability of Ferris Bueller and the looks of Don Draper.