As we approach the 25th anniversary of the 9/11 terrorist attacks, some survivors are reflecting on the tragedy. “It’s been 25 years, and without both of them I would’ve never made it out,” Marilyn Willis, a survivor, recalled in the “9/11 Reunited,” trailer. “That bond will always be there between us.”

The “9/11 Reunited” trailer, which USA TODAY can exclusively debut, examines the terrorist attack that killed nearly 3,000 people and honors the connections formed amid the courage and the chaos. The National Geographic docuseries features interviews with survivors, first responders and witnesses who reunite with the strangers and rescuers who changed their lives on Sept. 11, 2001. The docuseries will premiere Aug. 21 on National Geographic and be available to stream on Disney+ and Hulu Aug. 22. Producer Louis Lee Ray called it a “huge honor” to work on the series.

“Being there as survivors reunited – many for the first time in 25 years – was a privilege for all those involved,” Ray told USA TODAY in a statement. “Like everyone alive that day, I can remember exactly where I was when the attacks took place, but it was only working on the series that gave me a proper insight of what it was like to be there and live through it.”

Bill Spade, a former firefighter featured in the docuseries, was helping people evacuate from the lower floors of the World Trade Center’s North Tower when the building collapsed and killed John D’Allara, an emergency service police officer.

“Although John and I only worked together for a short time on September 11, I feel we accomplished a great deal,” Spade wrote in a statement to USA Today. “Through our actions, many lives were saved.”

ABC News will also air a slate of programming to commemorate the 9/11 attacks. This includes a Sept. 1 primetime special hosted by “Good Morning America” co-anchor Michael Strahan on how sports and entertainment helped the nation heal, and a one-hour live special, “9/11 Tribute in Light: Live from Lower Manhattan,” on Sept. 11. Newscasters David Muir, Robin Roberts and Diane Sawyer will host.

“9/11 Reunited” was directed by Julian Jones and created in collaboration with the 9/11 Memorial and Museum and production company 72 Films.

“Our hope in telling these stories is that viewers will see that humanity and kindness shines through even on the darkest of days,” producer Ray says.