Dozens of photographs taken by the New York City Fire Department and newly released by the government provide a sobering reminder of the conditions at ground zero in the aftermath of the Sept. 11, 2001, terrorist attacks on the World Trade Center.
They show, among other things, firefighters climbing atop the massive piles of rubble in darkness, hours before large generator-powered lights were brought in to the scene. Some photos offer a close-up look at the massive debris filling lower Manhattan streets. Others show the thick gray ash and countless pages of white office paper that settled over the devastated area.
"We all have particular photographs seared into our visual memories, but this is progressive drama – it's breathtaking in the most horrific way," said Jan Ramirez, chief curator of the National September 11 Memorial and Museum. "It's very important for people to be able to see this."
Click here to watch Jan Ramirez narrate the 9/11 images.
ABCNews.com first published a small sample of the collection that included aerial photos taken by New York City Police Department helicopter pilot Greg Semendinger. A second set of Semendinger's images was released earlier this week.
The rare aerial shots offer a visual narrative of Sept. 11: tugboats and commuter ferries racing to the shoreline near the burning twin towers, the dust and debris plume engulfing lower Manhattan, and the blanket of ash that covered the ground.
Many of the shots are from angles and perspectives not widely seen before.
"They're exceptional," Ramirez said in an interview with ABC News. "When you see this aerial body of work, you are given the rarest overview quite literally of this event as it's transpiring over the full 102 minutes and rest of the day."
The images taken by firefighters on the ground in the immediate aftermath of the buildings' collapse are particularly compelling for their intimacy with the surreal landscape and the level of detail they provide. The streets around the destroyed towers are choked with ash and paper.
"We look at that dust now for an entirely different view of what it represents," said Ramirez. "[It represents] the people that would never come back and, sadly, the health consequences it also caused for thousands of people who came to help thereafter."
Ramirez said the National September 11 Memorial and Museum, which is also collecting thousands of images from the tragedy, has obtained baggies, juice bottles and jars full of the pulverized residue scooped up by New Yorkers in the days after the attacks. "They did it not really knowing what it meant yet, but sensing there was something almost nuclear about it that they felt they should save," she said.
The museum's collection, expected to open to the public in 2012, also includes artifacts from ground zero, personal effects and memorabilia, expressions of tribute and remembrance, and oral histories given by survivors of the trauma.
Ramirez says some of the most poignent items include selected samples of the white paper that blew across the city after the office buildings were struck and captured in photos from that day.
"Many New Yorkers literally pulled it from their fire escapes and from the window jambs of their apartments and have kept it over all these years…We've been able to trace back and realize -- this is a business card, this was a document, this was a desk memo pad that came from the desk of someone unfortunately who perished that day," said Ramirez.
The extensive collection of newly released photos includes work by both amateur and professional photographers who submitted their images to the National Institute of Standards and Technology (NIST) during their investigation of the World Trade Center towers' structural failures. The photos were released following a Freedom of Information Act request filed by ABC News last year.
Ramirez says that while the collection retains tremendous emotionality for people who view it, the photos offer a meaningful reminder of just how far we've come.
"Although 9/11 was an event that certainly set in motion a cascade of political consequences and economic consequences, it is ultimately a great revealer of the human spirit. It was a moment when the essence of who you were -- what you were able to do under extraordinary circumstances, how you could help, how you could comfort -- was revealed."
ABC News' Jason Ryan, Pierre Thomas, Jack Cloherty, Lisa Jones and The Associated Press contributed to this report.