NEWTOWN, Conn. (CBSNewYork/AP) — It was five years ago Thursday that 26 innocent lives were taken at Sandy Hook Elementary School in Newtown, Connecticut – 20 of the victims children.

Connecticut Gov. Dannel P. Malloy directed all U.S. and state flags to be flown at half-staff Thursday in remembrance of the children and educators killed in the massacre on Dec. 14, 2012.

Meanwhile, the victims’ families and first responders were talking about how they have dealt with the pain by making it their mission to help save lives across the country.

Back in December 2012, Daniel Barden, 6, had one request from Santa – to meet him. His mother and father never got to answer his letter.

“There are many times where I’m still — Jackie and I are both still trying to figure out what happened to our little Daniel,” said Mark Barden.

The horror of the scene around the Sandy Hook Elementary School remained fresh in the Bardens’ minds five years later.

Adam Lanza, 20, made his way into the school and fatally shot 20 children and six staff members on the morning of Dec. 14 five years ago. He later took his own life.

Before the inexplicable tragedy, Lanza shot and killed his mother at their home.

“Sometimes, time feels like it’s going way too fast, and other times, it’s not moving at all,” Barden said.

But Barden has a few important round-the-clock jobs –being a husband and father to two teenagers, but also protecting kids around the country.

Just days after the tragedy, he became one of the founders of Sandy Hook Promise. Its mission is to help save lives by training adults and students to know the signs of gun violence.

“The guy who did what he did — if one more conversation, maybe one kid like Daniel going over to sitting down with them could’ve made all the difference. We will never know,” Barden said. “If somebody is talking about self-harm, connect them to a trusted adult and get them the help they need. That’s stuff Daniel used to do. So, I feel like I’m truly, tangibly honoring the way he lived his life through the work that we’re doing at Sandy Hook Promise.”

Barden said to date, his organization has trained 2.5 million students and adults in all 50 states on what to look for and how to respond.

He said what has been really rewarding is getting positive feedback from students he has instructed on how to treat classmates who appear isolated.

“They took that seriously and they’re doing it, and it’s spreading,” Barden said.

That comment came after Barden addressed a group at Eisenhower Middle School in Wyckoff, New Jersey back in October.

“We are getting evidence from the field that we have prevented suicides; that we have stopped mass shootings,” he said.

Other organizations, like the Kowalski’s youth triathlon program, honor the passions of the children who were lost.

“You have two choices,” said Rebecca Kowalski, whose 7-year-old son, Chase, died in Newtown. “I could be in the bottom of a bottle; I could not get out of my bed. Or, I could do what’s making us heal a little bit every day.”

Others have jumped into the policy fray to lobby for gun control or improved mental health care. In some cases, they have traveled the country, and even the world, as recognized experts in their fields, such as Jeremy Richman, a scientist whose Avielle Foundation for the study of brain health is named for his slain daughter.

Still, every single day for five years, the Newtown families have felt unbearable pain. The Bardens said their hearts go out to the first responders and what they had to deal with the second they arrived in Sandy Hook.

Retired Connecticut State Police Lt. J. Paul Vance not only had to walk into the heartwreching crime scene at the school. He had to keep his composure while updating the media as the number of lost lives kept on increasing.

“That particular day was probably one of the most tragic, horrific scenes that I’ve ever seen in my professional career over 43 years,” Vance said.

When asked how he did it, Vance said, “You know, your training kicks in; you do what’s expected of you.”

But Vance remembers the hurt evident on all of the faces he saw.

“It kind of hits you. It’s like a slap across the face,” Vance said. “You start thinking about the whole incident. You start thinking about your own family.”

Vance said it is painful to turn on the television and see more and more mass shootings.

“I don’t think they’re preventable, personally,” he said.

His only hope is, “We do the best we can to be ready to respond to them and by learning from each other in law enforcement and other venues, we can make our ability to prevent these things just a little bit better.”

As for the Newtown tragedy, both Vance and Barden will never forget the crowds of people from all over the country who traveled to the town to show support. But moving forward, Vance said, “I’ll take a little time by myself to think about the families to remember the victims.”

The Sandy Hook families have created a website to share each of their stories and information about the various projects they have started in memory of their family members.

The town is also creating a permanent memorial on a five-acre plot of land.
“I feel like I’m truly, tangibly honoring the way he lived his life through the work that we’re doing at Sandy Hook Promise,” Barden said.

Remembering The Child Victims Of The Massacre

Charlotte Bacon, 6;
Daniel Barden, 7;
Olivia Engel, 6;
Josephine Gay, 7;
Ana Marquez-Greene, 6;
Dylan Hockley, 6;
Catherine Hubbard, 6;
Madeleine Hsu, 6;
Chase Kowalski, 7;
Jesse Lewis, 6;
James Mattioli, 6;
Grace McDonnell, 7;
Emilie Parker, 6;
Jack Pinto, 6;
Noah Pozner, 6;
Caroline Previdi, 6;
Jessica Rekos, 6;
Avielle Richman, 6;
Benjamin Wheeler, 6;
Allison Wyatt, 6.

(© Copyright 2017 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)