Many will gather for a memorial service Tuesday night. Others tell say The Early Show national correspondent Hattie Kauffman they just don't know how they'll mark the moment.
Showing a picture of her daughter Kelly, Dee Fleming says, "This is our sweet girl."
Kelly Fleming wanted to be a writer at 15 years old, when she was gunned down in the library of Columbine High School.
Asked if it her grief has eased, Fleming says, "It gets easier, but it still comes back and punches you in the gut sometimes."
Her husband, Don, says he has gone through almost every single emotion: "Anger. Guilt. Sorrow. No joy, though."
Lauren Townsend was a straight-A student. Her mother, Dawn Anna, says, "She had so many plans, so many hopes, so many dreams." Lauren was a senior, just weeks away from graduation.
Dawn Anna says, "It's a hole that is never filled. The dance continues, but you dance with a permanent limp."
Even those who survived the school shooting still feel it.
The most searing memory for Erin Walton is "walking by dead bodies."
Erin was a sophomore at Columbine. She says, "I was 15. You're not supposed to see dead bodies when you're 15. But that day, everything just seemed to crumble."
She was holed up with other students inside a classroom. With them was a teacher who'd been shot and was slowly dying.
Looking at a yearbook, Erin says, "Here's Mr. Sanders. He was more worried about comforting everybody else than himself, and he was laying there dying! I think he was everybody's angel that day."
He was an angel who saved lives. Looking at the, it shows that while most raced to escape the gunmen, the teacher, , is seen going up the stairs, farther into the building, to warn students.
Erin says, "That man's running towards his death and he does not care. It didn't, he didn't, think about it twice."
He just wanted to get the kids out.
Erin says, "He's a hero in every child's eye that was in there that day."
Columbine softball coach Rick Bath says, "What he did that day doesn't surprise me."
Bath coached with Dave Sanders for 19 years at Columbine. Sanders' death, Bath notes, "left a huge hole."
Frank DeAngelis, the principal of the school, also coached with Sanders. "We coached together, we laughed together, we cried together, and he probably saved my life that day," DeAngelis says.
He retells his story to The Early Show co-anchor Harry Smith: "My worst nightmare came true. I'm walking out, the gunmen's walking in. And I see a shotgun being pointed at me. 'Til this day, I did not realize why they didn't shoot me, but I found out a few weeks ago when I looked at the evidence. It was Dave Sanders, who came up the stairs at the time I came out of my office. And the gunman stopped his pursuit of me, went after Dave and shot Dave in the back. So, it's tough. It's tough to handle."
Just outside, in what is now the Dave Sanders Memorial Softball Field, are bricks filled with tributes: "Thank you, coach", "Always in our hearts", "Forever with us."
Erin says, "There was good in Mr. Sanders. There was good in everybody. The only evil that was there was in Eric and Dylan that day. And it died with them."
Faith has helped some families. Kelly Fleming's parents have angels throughout their home. Still, their daughter's last moments haunt them.
Don Fleming says, "It's very painful to think about what happened. She saw it coming. They all knew. I mean, she was shot pointblank, so she was looking down the barrel of a gun."
Parents are supposed to. But Don Fleming says, "We couldn't that day."
Dawn Anna still remembers the last words she spoke to her daughter, Lauren Townsend. "'I love you. See you at 2:40.' Would I say anything differently to her if I could see her again? No. Would I do something differently? Yes. I'd throw my body over her. I'd get her out of there."
Just weeks after the massacre, Columbine seniors graduated. Lauren Townsend was supposed to be valedictorian. Instead, her mother carried her cap and gown across the stage.
That moment for Dawn Anna was "huge," she says. Lauren's stepfather says, "The feeling from that crowd was just unbelievable. I mean, you know, goose bumps."
Surviving students, like Erin Walton, don't take anything for granted. Her relationship with her own parents has changed forever.
She says, "We're not a family that says 'I love you,' but there are those days where you just, like, 'I really love you! And I just want you to know that I'm proud to be your daughter.'"
There's something good that came out of that tragic day. She says, "It brought me closer to my family, and it made me realize I don't have it so bad. I have parents who care for me. And they show it."
Mike Johnson, who was in the school that day and suffered multiple wounds tells The Early Show's Smith the most important thing he learned from the tragedy was to lean on God.
He says. "I think that my faith was definitely strengthened. I was able to learn that as we go through challenges and trials in our lives, that as long as we have faith in God, He'll bring us through and that we will be able to grow and learn from the situations that come into our lives."
Mike is one of the authors of a book called "Surviving Columbine" that's out now. Darryl Scott, who lost his daughter, Rachel, has been trying to teach kids, parents and school systems about what the important lesson of that day was through a program called, "Rachel's Challenge."
"We've been in around 800 schools around America, and Bermuda. We've seen school shootings prevented because of the program," he says, "We feel like if we can touch the hearts of young people, they'll open their heads for instruction. So our assembly is a one-hour assembly for the whole school. It's a very powerful, emotional assembly about Rachel's life and a little bit about the tragedy. Then, we follow that up with two hours of training with a cross-culture of the school and ask for students that are on the perimeter, as well as popular kids, to be a part of that."
The program aims to reach out to kids who are on the periphery. Scott notes, "Rachel wrote an essay the month before she died. In the essay, she wrote: 'We need to get a chain reaction going of kindness and compassion.' Eric Harris, the one who killed her, at the time she wrote that, was making a video and saying the same words: we need to start a chain reaction. We can contrast the two."
Tom Mauser is also doing something in the name of his slain son, Daniel. He has been working hard to get background checks at gun shows. Apparently, some of the weapons that were used five years ago came from shows, where there was no background check at all.
But his job has not been easy. He says, "It's been quite a trip, trying to get to change people's minds, and just move towards more reasonable gun laws."
But some progress has been made, he notes. "Here in Colorado, we passed a law to close the gun show loophole. Seventy percent of the people in this state, the voters said, yes, we want to do that. Now, we're working on the assault weapons ban. It's going to be expiring in September, unless Congress and President Bush extend that assault weapons ban. So we're working hard on that."
He has also published a Web site, danielmauser.com, to focus "on the lives that were lost and not just focus on the killers. We also adopted a baby girl from China, as part of our healing process. It meant a lot to us," he says.