Dr. Mark Elliott still wears a Columbine pin on his lab coat.

Elliott, who runs the medical team at Littleton Adventist Hospital, said April 20, 1999 is vivid in his memory.

“We didn’t get the most serious victims, but we got the most numbers of victims,” Elliott said. “The normal emergency room volume and walk-ins shut down. People knew something was going on, and I think they stayed away partly out of respect.”

Two decades later, Elliott said he still meets people affected by the tragedy all the time.

“It made me realize that something like that could happen anytime. It made me more empathetic. You never know what kind of trauma someone has in their life.”

To this day, Elliott said, the hospital’s medical teams are affected by other shootings.

“Every time there’s another, and people mention Columbine, we feel it. The ER group will send cards to that ER. We say: ‘We’re thinking about you. We know what you’re going through.’”