New York City: They were among the heroes of the September 11, 2001 attacks, the first responders who rushed to the World Trade Center site to search for survivors.
But they worked mostly in anonymity.
Now, photographer Andrea Booher pays tribute to the men and women who toiled at "the pile," with a showcase of her work in the "Hope at Ground Zero" exhibition opening Friday at the National September 11 Memorial and Museum which now occupies the site in downtown New York. It runs through May 2017.
"In the beginning it was firefighters, volunteers, search and rescue, police. Everybody had sort of a different approach to how they were searching for survivors," she said. "The only goal was trying to find survivors in the pile."
Booher, a photographer for the Federal Emergency Management Agency (FEMA), had arrived at the site the evening of September 11 and was assigned along with colleague Michael Rieger to document the aftermath of the deadliest terror attack on US soil.
She ended up staying two and a half months.
"I really felt that it was an incredible honor but it was a lot of responsibility," she said. "I pushed myself to my limit workwise and in every aspect."
In the early days, the work was frantic as rescuers searched for survivors.
But around September 20, "I showed up at the site. Nobody said anything, but it was just like this very depressing feeling, very heavy feeling at the site," Booher said.
"It was kind of rainy, and it was just... there was no energy. You had just the feeling that it was over, that the hope was gone. We weren't going to bring (out) anyone else. It kind of switched to a recovery mission at that point."
Twenty people were found alive in the rubble, the last one September 12. In all, the attack in New York claimed 2,753 victims.