(CNN) The rifle-carrying National Guardsman must have been in his early 20s. Just weeks before, the young man would have been out of place on Vesey Street in lower Manhattan.

But on the day "Third Watch" executive producer Christopher Chulack saw him from the backseat of a NYPD police car as he drove up to Ground Zero -- escorted by dust-covered New York City police officer Mike Keenan at the wheel -- a fresh swarm of uniformed reservists had just descended upon the area.

Keenan was a technical adviser on the show, a drama about people who ran into buildings and situations that other people would run away from. Like many other real-life firefighters, paramedics and police officers who had become a part of the drama's fabric over the first two seasons, he had reported to the scene on the morning of September 11, 2001.

It was the start to a surreal few hours that Chulack, best friend and "Third Watch" co-creator John Wells, and two others from the show spent meeting some of the men and women sorting through a stories-high mess of powdery debris and twisted metals while breathing still-hazy air.

Their visit was in prep for what would be days of on-camera interviews with first responders -- some of them colleagues and friends -- who had weeks before been witness to one of the grimmest days in American history. About 40 conversations with real-life first responders followed and turned into a two-hour special called "In Their Own Words," a collection of first-person accounts that even 15 years later stands as one of the most compelling and emotionally-stirring tributes to 9/11 first responders.

"I'll never forget, I said to him, 'I'm glad I saw this,'" Chulack told CNN in a recent interview. "And John said to me, 'I'm not sure I'm glad I saw it.'"

For the veteran TV producers, they remember it as a rare moment where they had to capture tragedy that wasn't being created, but lived.

How to make it work

In the immediate aftermath of 9/11, Wells and the "Third Watch" team were focused not on the show itself, but on their people. Based in Los Angeles, he and others took to the phones -- even though communication with those in the city was spotty at best -- to check in with everyone.

They found ways to assist from afar. The show sent set lights, catering equipment and even a fire engine down to Ground Zero in the days after. Much of the Fire Department's real equipment had been damaged, so the show lent whatever resources they could.

Wells, meanwhile, had to figure out how the three shows he executive produced -- "ER," "West Wing" and "Third Watch" -- would address the events of 9/11.

"You're immediately confronted with the question of what you are going to do to respond to such a huge and extraordinary event that was affecting the psyche of the entire nation," he said. "I don't want to overstate what entertainment's part in that is or isn't, but you know [the attacks] were all anybody was thinking about. We were all shocked and traumatized throughout the country."

That included the people who worked on the show. In the emotionally charged days right after, in fact, there were some who wondered whether the show could go on at all.

"I think we were very aware of the fact that we were treading on thin ice in terms of how do we go back," cast member Molly Price recalled. "I guess there was this period where we all thought, 'Is the show going to get canceled?'"

Big meetings and "heated discussions" took place, Chulack remembers. He was among the dubious.

"First of all, we worked with people who were dead now," he said. "And for the people on the show, do they really want to do this show? And do we really want to travel the streets of New York City and tell cheesy stories about Ground Zero?"

As emotions calmed, communication with New York was restored and feedback from their on-the-ground advisers came in, there was largely a change of heart. Maybe they could do the show.

Like the characters the actors portrayed, the show itself was suddenly being called to duty -- to find a way to honor the people who gave up so much on that day in September -- and they were determined to deliver.

They decided the best way to do so was with the truth.

John Wells, Molly Price and Christopher Chulack

'Are you sure you really want to hear this'

Almost every interview would begin the same way, according to Wells.

First, the person in the chair would start by telling a guarded, tame version of events of 9/11 -- something they'd maybe tell a loved one who they didn't want to alarm. Then it was on interviewers to try to get past that, Wells said.

In doing so, he'd often be met with the same response: "Are you sure you really want to hear this?"

Wells said he knew it was the instinct of first responders to protect those around them -- to stop themselves from telling stories that might be too much for the people around them to handle. He'd seen it before while filming an episode of "China Beach" where they interviewed real-life veterans. But Wells wasn't interested in the details one might find sensational; he wanted the human stories.

"We were just trying to get at what really happened to these men and women and to the other members of their family," Wells said.

The details still hit Chulack hard to this day. Some of them aired, others didn't.

He remembers sitting on the bumper of a fire truck as a young EMT recalled correcting his partner when he saw what he thought were dead pigeons on the ground. They were body parts.

He recalls the usually unflappable Keenan talking about the father who identified his son by a femur that had been repaired with pins during surgery years ago.

He still remembers the strength of the five women who came upon the crew during one of their stops at a fire station -- the interviews were often conducted in active firehouses and police stations -- and volunteered to speak to them while their husbands were still missing.

Wells said it was harder to interview people they didn't know because there was already a growing discomfort among first responders with the word "hero." Interviewees "wanted to hold on to and remember their friends as who they were, not as symbols," he said. The producers were sensitive to that.

Cast of "Third Watch" Molly Price, Anthony Ruivivar, Michael Beach, Jason Wiles, Coby Bell, Eddie Cibrian, Kim Raver, Skipp Sudduth, Bobby Cannavale

Price was among those interviewed. While her cast mates filmed special intros for each segment of the special, she was the only series regular to actually sit for an interview. (Several recurring cast members were also interviewed.)

On the show Price played Faith Yokas, an unshakable cop and married mother of two who as the primary breadwinner in her family shattered gender roles long before it became common to see it done on TV.

On 9/11, Price was headed out with a stack of dog-eared bridal magazines in hand to pick out her wedding dress. She had been dating firefighter and "Third Watch" cast member Derek Kelly for two years after meeting him on set during the pilot.

It had been a secret at first -- very romantic and exciting, she remembers. They were set to be married October 13.

That morning, Kelly called her and said he was headed to the World Trade Center and that she should turn on the TV and not leave the house.

She didn't hear from him again until close to 9 p.m. that night. When the phone rang, she said she knew it was him.

At first, Price didn't want to take part in the "Third Watch" special. She's "a very private person," she said. But something got her in the chair.

"I guess I got sentimental," she said. "I thought about all the people who had died, and I thought about all the women who had lost their husbands, or husbands who had lost their wives."

She added: "I think it was very smart, very good television, and very important in terms of being responsible and being a responsible producer of television. I think John is that."

Remembering

"In Their Own Words" aired October 15, 2001. The telecast averaged 9.7 million viewers and a 3.6 rating among adults 18-49, according to NBC's records.

It won a Peabody Award in 2001.

Wells said the special stands as one of the things he's proudest of having been involved in -- but he is mindful not to overstate his or the show's value. He's a man who makes TV shows for a living to entertain people, he said. If he's lucky, every now and then, those shows provide a little more than that.

"I think it's natural and normal in human nature to take tragic events that are so powerful and find some way to give them a narrative that makes sense and then move on," he said. "But I thought it was important to not let it be quite not that simple in our own small way."

In the episodes that followed "In Their Own Words," "Third Watch" never forgot 9/11. The series had two more episodes directly related to the tragedy and the reverberations were felt for seasons to come. A character lost her father in the towers. Another struggled with PTSD. Seasons later, another had a breakdown stemming from the tragedy.

The first two seasons of "Third Watch" are available for streaming, but the subsequent seasons -- including Season 3, during which this episode was broadcast -- have gone unreleased for years due to music rights. (Replacing the popular music used in the show with some that is cleared for streaming is a pricey process.)

But Chulack remains hopeful "In Their Own Words" will air again.