Given how quickly photographs are spread by the news and social media, we’ve come to assume that if photos of an historic or catastrophic event are available, they’ll be available in large numbers and almost immediately. But a recent Associated Press article suggests that’s not always the case.

A small number of photos shot by now-retired NYC Police Detective Greg Semendinger, the only policeman allowed in the airspace around the World Trade Center on 9/11,  were only recently released by the National Institute of Standards and Technology, the government agency that investigated the towers’ collapse, and only after ABC news filed a Freedom of Information Act request for them, last year.

In spite of all the images of 9/11 that have been published or broadcast, these previously unseen pictures are startling for the seemingly objective overview and perspective on the scene that they provide. Most of the photos and video we’ve previously seen—shot at or from street level, from windows and rooftops in Manhattan, or from the shores of Brooklyn or New Jersey—capture the shock, drama and tragic aftermath of what transpired in 2001, but from conventional journalistic perspectives. Seen then and to this day, it is hard to view them without having a visceral reaction to the destruction and aftermath they depict. (A clip from YouTube shows the Twin Towers, the police helicopter circling above (starting around 1:10), and the collapse of the first building.)

In a piece David Friend, author of Watching the World Change: The Stories Behind the Images of 9/11 (Farrar, Straus, Giroux, 2006), wrote for click! photography changes everything, he described the central role photographic images played in telling the story of 9/11 as it unfolded. “What mesmerized each observer, surely, was the gravity of sudden death, in numbers of such magnitude. But they were also gripped by the pure visual spectacle—by the sense that this irreconcilably infernal scene was somehow meant to be seen .... The attacks were considered the most photographed breaking news event in human history, witnessed on television and the Internet that day by an estimated two billion people—a third of the human race.”

What the newly released photos depict is different from what we know and have come to expect—a God’s-eye view of the scene in which the carnage, panic and bravery on the ground don’t register at all, at first.  What dominates, instead, is billowing smoke and ash, which we now know was made up of building and airplane debris and human remains. These cool, forensic images were probably invaluable to investigations, but they are chilling to re-consider now, as we try to connect the near-abstract and dispassionate views from above with what we know was experienced down below.

"I almost didn't realize what I was seeing that day," Semendinger, told AP.  Looking at it now it's amazing I took those pictures . . . It was surreal.  There was no sound. No sound whatsoever, but the noise of the radio and the helicopter. I just kept taking pictures."