By Rob Johnson

(CBS) – In a week, it will be 10 years since the mass shooting at Northern Illinois University.

Not only did it change that campus forever, it also changed the lives of those who survived that horror.

“A guy in a long trench coat walks in, doesn’t say a word, pulls out a shotgun and starts shooting at us,” Patrick Korellis tells CBS 2’s Rob Johnson.

It happened shortly after 3 p.m. inside NIU’s Cole Hall.

The shooter killed five students and injured more than 20 others, including Korellis.

“I felt something hit me in the back of the head,” he said. “I looked and my hand was bleeding.”

Korellis graduated later that spring. Harold Ng, a year later.

Though the survivors weren’t close before, they are now.

“We’re forever bonded by a tragedy, and we do the best to help lift each other up in these difficult times,” Ng says.

Cold, crisp days remind Kelly Wesener Michael of what happened 10 years ago. Now dean of students, she spoke with Johnson in what used to be the classroom where the shooting happened. It’s now an anthropology museum.

“We decided we had an obligation to educate our colleagues,” she says, “about how to be ready, how to respond.”

A memorial is a reminder of that violent Valentine’s Day a decade ago, the names of those murdered etched in stone. While the university knows this tragedy is part of its history, it doesn’t want to be defined by it.

“I think all us live our lives a little bit different knowing how quickly, in just a heartbeat, it all changes,” Michael says.

This journey is also about those left behind, like Joe and Laurel Dubowski, whose daughter Gayle died that day. She never got to walk across the stage at graduation, but in 2012  her father did, earning his master’s.

“I’ve been working with grievers for the last eight years or so,” says Joe, who changed careers after the tragedy.

Korellis works full-time at Walgreens corporate offices and lives with buckshot in his arm and head.

“I still have a sharp pain when it gets really cold, the back of my neck,” he says.

Ng is working on a second book about overcoming tragedy, but still has moments of angst.

“Big, loud noises — I still tend to shy away from those,” he says.

Ng and the others will return to campus Friday when memorial events begin for survivors and the families of victims.

“I’m looking forward to seeing people. It’s going to be hard, but we’ll be together,” Dean Michael says.

A new exhibit of the shooting opened at NIU this week. Starting Friday and running all weekend there will be private and public events to acknowledge that dark day.

Next Wednesday, there will be a vigil on exactly 10 years after the shooting.

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