Correspondent Harold Dow was reporting from Columbine High the day of the attack, when he first met the daughters of Dave Sanders. Sanders was the only teacher killed that day.
"Instead of feeling sorry for himself or anything like that, he said, 'Tell my girls I love them.' And here we are," says Connie Sanders.
Today, Connie and her sister, Angela, still grieve, but they have learned how to live without their father. Still, there was something different about the death of Dave Sanders, who coached basketball and taught business courses -- something his family has struggled with these five long years.
"I strongly feel like my dad should still be here today and he's not," says Angela. "It was a complete and total communication breakdown," adds Connie.
"I learned so much from Dave, a very caring man, a very compassionate man. He got into education for all the right reasons. He loved kids," says Columbine Principal Frank DeAngelis, who began his career as a young teacher and sports coach alongside Sanders. They taught together for almost 30 years.
On April 20, 1999, as the sun rose over the Rocky Mountain town of Littleton, Colo., Sanders came to school as always, ready to teach.
But for months before that, Eric Harris, 18, and Dylan Klebold, 17, had been plotting a dawn different from any other. Showing off for a home video camera, the two angry outcasts had been busy buying guns, building bombs, and rehearsing mass murder.
That day, they came to school ready to kill. The shootings took place at 11:19 a.m., in the corridors of Columbine High School.
"I came out of the office here. And as I was walking down, right where those doors are located, that's where the gunman was coming in," recalls DeAngelis. "And that's when I realized, 'Oh my God, this is happening.'"
School surveillance cameras would capture Klebold and Harris coldly hunting down their classmates. Children like Erin Walton and Kristi Held remembered running for their lives.
"Someone just running down the hallway said, 'Someone downstairs has a gun,'" recalls Kristi.
In the library, students were being executed one by one. The instinct was to flee, unless you were a teacher like Sanders, who headed straight towards the gunfire.
"That picture will always stick in my mind, that he was running into it instead of away," says Erin.
"He apparently went up there to make sure the kids were getting out of harm's way," says Rich Long, Sanders' colleague and close friend. "And then, just as he turned the corner into the hallway, that's when Dave was shot."
The school cameras would actually photograph Dave Sanders being shot twice. Rich says he helped his friend to safety after he was shot. Bleeding profusely, Dave Sanders was brought to Science Room No. 3.
But bullets were still being fired in the chaotic hallways of Columbine. In Science Room No. 3, a different struggle began, as the students Sanders mentored and taught struggled desperately to save the life of their teacher.
"He was bleeding pretty bad," says Erin. "And it was serious … We couldn't exactly do much. We just gave up clothing that we could to help stop the bleeding. That's what we were really concerned about."
They also put a sign in the window in hopes of getting help from the outside.
"I looked up in this one window and saw a small handwritten sign on cardboard that said, 'One bleeding to death,'" recalls Senior Agent Don Kraemer of the Lakewood Police Department. Kraemer was a member of the SWAT team that was in the Columbine parking lot. "As things developed, I realized there was somebody in there that needed help."
But police decided to keep the cops and the medics out of the school until they had more information as to what was going on. They would later be severely criticized for their actions. "It was frustrating," says Kraemer.
Even after Klebold and Harris had committed suicide, help stayed rooted cautiously on the outside, as Dave Sanders lay dying inside Science Room No. 3.
Erin says that she and other students stayed in the room for about four hours: "He [Dave Sanders] was bleeding the entire time."
"I tried to encourage him," says Long. "I said, 'Dave, you're going to be fine. We're going to get you some help.'"
The students snapped legs off a table and built a makeshift gurney to carry their teacher out. That's when a SWAT team finally arrived.
"They told us that they wanted all the healthy people out first," recalls Erin, who says she believes that Sanders was alive when she left. "They wouldn't let us use it."
"In reality, they forgot about him. He was still lying in the school," says Sanders' daughter, Angela. "He turned into a piece of evidence," says her sister, Connie.
"I think that was the biggest tragedy of Columbine High School," says Long. "You know, there were 23 miracles -- 23 kids that were shot and all survived. Dave could have been one of those miracles if he would have had treatment."
"His last words were probably the most thoughtful of all. He said, 'Tell my girls I love 'em.' And the neat thing is that could have been us," says Connie. "That could have been his softball team. That could have been our mom. Everybody was included in those last words."
Angela Sanders would sue the Jefferson County Sheriff's Department. Of all the lawsuits against local law enforcement, it would be the only one not dismissed.
"Eric and Dylan caused my dad's injuries, but the lack of response from the police department is ultimately what killed him, what caused him to die," says Angela, who eventually settled her lawsuit for $1.5 million.
The judge would also write that: "Police showed a deliberate indifference towards Dave Sanders' plight."
The Jefferson county police have since revised their tactics to immediately enter a school in the event of a shooting.
"And I think law enforcement has learned through this," says Angela. "I really think a lot of lessons have been learned through all this. And once again, Dad is the teacher."
It's peaceful now in the hallways of Columbine. Signs of spirit and renewal are everywhere. But things will never be the same. Every day, a police officer is on duty. And just a short walk from where Sanders was shot, a ballfield has been named for this coach and teacher, so no one will ever forget his endless capacity to help kids -- and what went so horribly wrong five years ago.
"Someone once said, 'When will it be back to normal at Columbine?'" says DeAngelis. "It will never be back to normal. What happened April 20 will be with us for the rest of our lives."
"It's been five years," says Sander's daughter, Connie. "And we still think about it at least once every day."
Next Tuesday, Columbine High plans to mark the fifth anniversary of the attack quietly – no school, and a ceremony of remembrance at a nearby park.