(CBS News) BOSTON -- The photo has become the iconic image of the Boston bombings: seconds after the blast, a runner knocked to the ground, stunned police officers responding in different directions. Boston Globe photographer John Tlumacki was behind the lens.
"It was confusion at first," he said, when asked what was going through his mind when he took the photo. "I reacted instinctually. My senses just took over. My camera was on my face, and I just kept shooting."
Tlumacki said that when he ran over to where the bomb went off, he saw "bodies on top of bodies."
"Pools of blood, there was smoke. It had that Fourth of July smell to it -- after the grand finale, and I saw people in agony," he said. "I remember seeing this man who was comforting this girl, and he was holding her hair and her head, and he was whispering to her, and that was one of the first pictures I took."
"There were people, you know, taking their shirts off," Tlumacki remembered. "There were bystanders putting tourniquets on people's legs. It wasn't just one photo or two photos, it was a series of photos that showed, you know, the commitment, that -- that compassion that people have in Boston for each other."
Asked to describe the emotions he was feeling, Tlumacki said, "I felt just like crying. I felt like -- you know, I knew I couldn't stop. I just felt like there was so much going on, and my best chance for doing anything useful there was to -- to just keep shooting pictures."
The last photo Tlumacki took at the scene shows a woman kneeling and praying amid the chaos.
"She just was kneeling, and it was something so sacred about it," he said. "She just had the -- I don't know -- the respect to do that, just to take the time out and to pray."
He said while many of his photos captured the hell of that day, he took just as many that captured hope.