When two hijacked planes hit the Twin Towers on Sept. 11, 2001, firefighter Bill Spade reported to the North Tower to help evacuate survivors. He tried to make a mayday call over his radio but received no answer. With help from emergency service police officer John D’Allara, he broke down a jammed door, allowing people to escape onto the street level. 

Shortly after, D’Allara, an officer from Harlem, and Spade, a firefighter from Staten Island, found themselves discussing family. D’Allara mentioned his wife Carol, his seven-year-old son John and his two-year-old son Nicholas. Spade compared it to writing each other’s obituaries in real time.

“Our two units never really meshed together [before],” Spade tells USA TODAY. “And here we are, working together … in the middle of the towers, of all this catastrophe that’s going on, talking about our wives and kids. That doesn’t happen.”

Then, the North Tower collapsed, burying them and civilians under soot and debris. Spade made an airway to breathe by sticking his finger in his mouth. He later learned that D’Allara was killed during the tower collapse. 

In “9/11 Reunited,” a three-part docuseries streaming now on Hulu and Disney+, Spade sits down with D’Allara’s family for the 25th anniversary and recounts the tragic attack that killed more than 2,900 people. Their reunion is one of six stories highlighting the life-saving connections made among rescuers and survivors on that fateful day, from three men who used a squeegee to escape a stalled elevator to a first responder who spent nearly 24 hours buried under the rubble.

Julian Jones directed the National Geographic docuseries and tells USA TODAY he felt a responsibility to treat the survivors with the utmost care and respect, providing a team of psychologists and choosing filming locations they felt comfortable with. Jones, who worked on the project with the 9/11 Memorial and Museum and production company 72 Films, says the participants faced survivor’s guilt and felt an obligation to live life unabashedly. And as evidenced by Spade and the D’Allara family’s reunion, the emotional connections fostered on that perilous day have persisted through two decades. 

“We wanted to focus on a terrible, tragic, horrifying event where people just showed up for each other,” Jones says, adding the whole team was moved to tears during takes. “There was something about the human spirit there. People were willing to act selflessly for people they didn’t know, and that created lifelong bonds.” 

John J. D’Allara, a Marine reservist who shares the same name as his late father, says most of his memories of his dad come from secondhand accounts but he does recall gleeful moments playing with toys or visiting Sesame Street.

“What I have heard from other people is that he was a great person, somebody that you’d want on the job with you,” D’Allara, 32, tells USA TODAY. “Things that make you proud to be in his family.”

At home, the D’Allara family commemorates the fallen patriarch through a shrine decorated with an NYPD medal and diploma, judo trophies from his childhood, and family photos. But the docuseries gave his family a chance to honor him in a different way − by meeting up with Spade at his Staten Island, New York, home to recount Officer D’Allara’s final moments and lasting legacy.

“The whole process of us meeting Mr. Spade and his family, [with] my whole family, was pretty monumental,” D’Allara says, “especially because hearing stories about our dad and seeing the connection there, him being one of the last people to see him alive… my family is extremely appreciative.”

The reunion was equally as special for Spade. “I was with their dad for the last half hour of his life,” he says. “I always wanted to relay to them their dad’s last moments.”

Officer D’Allara ultimately helped save 20 lives on Sept. 11, according to the docuseries. He was among the 441 first responders who were killed during the attacks, the most emergency responder deaths on a single day in the United States, according to the 9/11 Memorial and Museum website.

Meanwhile, Spade is the only surviving member of his 12-person Rescue 5 team. He says the lead-up to the anniversary each year is always a difficult time, but he holds a Thanksgiving-style dinner with his family every Sept. 11.

“It’s all about family. When those towers were coming down, the only thing I thought about was my wife and my two boys,” Spade says. “Right before that, John was just thinking about his wife and his two boys. So we had that in common. And since that day, it’s been a goal of mine to never forget.”

Though 25 years have passed, Spade has stayed true to his word.

He gives talks at the 9/11 Memorial and Museum about 12 times per year, where he discusses Officer D’Allara’s legacy. Spade’s son Billy and D’Allara’s son have even become friends, completing humanitarian work as part of 9/11 nonprofit Tuesday’s Children, and have a photo featured in the museum to show for it.

And though Spade still struggles with his grief, he maintains his lifelong vow to never stop talking about the day that changed America forever − and the people he met along his journey.

“I relive it every day of my life since 9/11,” Spade says. “I’m sure John has thoughts of his father every day. So it’s the same thing. I always tell people I went to counsel[ing] for four years, but it doesn’t really leave you… by talking about it, I feel it’s better than keeping it inside.”

“Through me, the legacy of John D’Allara will always live,” he adds, holding back tears. “Even though we were only together for a half hour, 20 minutes, it was a lot of camaraderie between us. We saved a lot of lives.”