To mark the occasion, National Geographic is airing 9/11: One Day in America. Unlike previous series, this is told only in first-person narrative that chronicles, at times minute-by-minute, the events of that day from the perspectives of first responders and survivors who were there. It brings a very human reality to the historical event. Parade.com has an exclusive clip of survivor Tom Canavan recalling his escape from the towers, which appears in episode 3, airing tonight, entitled “The South Tower.” It opens with the announcement that people should remain where they are, but then those in the south tower watch with shock as the north tower is hit by a hijacked plane. When the second plane hits, civilians in the south tower have to find a way to escape from the top floors to safety. Paramedics at street level face an onslaught of both the badly injured and casualties and race against time to save lives. As Canavan walked away from ground zero, covered in dust, ash and bleeding, he was caught on film that day. He explained what happened: “Big boom. Coming down the steps everything was fine until we got to the basement and then everything just fell in. I was trapped under there with another guy and crawled out. I kept getting hit in the head and bashed around. We finally made our way out over the rubble.” The 9/11: One Day in America filmmakers Dan Lindsay and T.J. Martin spent more than three years interviewing 54 people and learning their personal stories before compiling them into the 7-hour docuseries. In addition, it will feature never-before-seen moments, such as footage taken of the towers from apartments and streets nearby just after the planes hit, the triage area right in front of the towers at the very early stages following impact, and intimate rescue missions during that terrifying day. “Our hope with this series was to bring to the forefront the true human experience of 9/11 in a way that would honor both the victims and the survivors of the attacks that day—a series that forgoes the geopolitical implications and instead focuses on the experience of the people that were there,” said Lindsay and Martin in a statement. 9/11: One Day in America will air over four consecutive nights on National Geographic with limited commercial interruption, beginning August 29, and then episodes will be made available next day on Hulu. Next, The Most Powerful Quotes Remembering 9/11 on the Upcoming 20th Anniversary