Never-before-seen photos from 9/11 have been released in the build-up to the 20th anniversary of the devastating terror attacks that brought the US to a standstill.
The US Secret Service this week has published new images that captured the destruction caused when two commercial planes crashed into the World Trade Centre's twin towers in New York's Manhattan in 2001.
And while there is a stream of images that document the horror of 9/11, the newly-released photos offer a glimpse into what secret service employees saw in the aftermath of the unimaginable attacks that claimed the lives of nearly 3,000 people.
In a photo shared on Wednesday (local time), the World Trade Centre can be seen collapsing in a plume of smoke with a church's cross in the foreground. Debris can be seen scattering into the streets below.
Another shows the destructions caused in the Secret Service's New York offices' car park with armoured limousines badly damaged amid piles of rubble.
One poignant image shows a lone first responder on an empty Manhattan street shielding his face from the resulting haze in apocalyptic scenes.
Further images are to be released by the Secret Service in the coming days.
It comes as US President Joe Biden last week ordered the the Department of Justice to review documents from the FBI's probe into the attacks for declassification and release.
"When I ran for president, I made a commitment to ensuring transparency regarding the declassification of documents on the September 11, 2001 terrorist attacks on America," Biden said in a statement.
"As we approach the 20th anniversary of that tragic day, I am honouring that commitment."
First responders describe ongoing pain 20 years later
As the US prepares to commemorate the victims who lost their lives in the attacks, those involved in the aftermath have relived the tragedy they faced in their response.
Now-retired Brooklyn inspector Timothy Pearson said he still "chokes up" when thinking of 9/11.
"When I do, I see the fear and I feel the fear," he said.
Mr Pearson managed to evacuate hundreds of people from the World Trade Centre site but says he is haunted by the image of those who could not be saved.
"As I'm looking up I see what I thought was one of the strangest things," he recalled.
"I'm wondering why there were birds flying down through the smoke."
"Then I realised they were people coming down - people."
Chief of Department Joseph Esposito had befriended former FBI terrorism expert John O'Neill and saw him the morning of 9/11 in his new role as head of security of the World Trade Centre.
The next time he saw him was on September 21, when he helped carry O'Neill's body from the wreckage.
He had returned to ground zero every day after the attack in a desperate search for survivors.
"After a while, I'm saying to myself, 'Why are we doing this?' There's nobody alive,'" Esposito recalled.
"But I realised it was therapy for the people who were there."
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