(NewsNation) — When he first heard about the shooting at Robb Elementary school in Uvalde, Texas, Frank DeAngelis was brought back to 23 years ago, when he was principal of Columbine High School.

The 1999 Colorado shooting, where two student gunmen killed 12 of their classmates and one teacher, was the worst high school shooting in US history at that point.

So when DeAngelis heard about the 19 children and two adults who died at the hands of an 18-year-old gunman, who was later killed by law enforcement, it regenerated “many of the feelings” he’d had surrounding the Columbine shooting.

“I can’t imagine what they’re going through at this point. Each family is different, and it’s a roller coaster ride,” DeAngelis said on “Morning in America.” “But one of the things that I can tell the people in Uvalde is we’re on this journey together. And we’re going to be there every step of the way. Because they are all of our kids. It doesn’t matter if it’s Texas, Colorado, Florida, they’re all of our kids.”

One of the most difficult things to face is the survivor’s guilt, DeAngelis said. It’s something he deals with himself.

“A dear friend of mine, Dave Sanders, unfortunately, lost his life. And if he did not come up the staircase at the particular time he did I wouldn’t be doing this interview,” DeAngelis recalled. “So there is that survivor’s guilt.”

This guilt, DeAngelis said, is something that can be helped with counseling.

“One of the biggest lessons that I learned is, people can go through the same event but how they deal with it, they deal with it differently,” DeAngelis said. “And there are going to be people that want to talk about it, other people, they’re going to be very quiet and want to be left alone, and people in between. We need to respect where everyone is and provide that help for as many people as possible.”

Before the shooting, DeAngelis said, the only drills that happened at Columbine were fire drills. But now, kids are learning about lockdowns, and other drills, in case their school is the site of a shooting like the one in Texas.

In this kind of situation, DeAngelis said, having a swift police response is important.

“There were so many lessons learned from Columbine,” DeAngelis said. “So having a an officer on campus, as opposed to waiting for a responding officer is so important.”

School resource officers are necessary, DeAngelis said, as most of these shooting events are over within five minutes.

“If you have someone in that building, protecting the kids, I think that is a valuable resource,” he said.