An ex FBI employee who was sent to the crash spot of Flight 93 on September 11, 2001, claims she witnessed a legion of angels guarding the area when she arrived.
Lillie Leonardi has made the bizarre claims in a book written, after she retired from the FBI due to post-traumatic stress disorder, which began after the terror attacks.
In the book, she explained she arrived at the still-smouldering scene three hours after terrorists hijacked the passenger jet and it crashed into a field in Shanksville, Pennsylvania.
Leonardi, who was brought up as a devout Catholic but says she now practices "spiritualism," was working as a liaison between law enforcement and the victims' families.
On her arrival, burning pine and jet fuelled stung her nostrils and the entire site was eerily silent, she writes in 'In the Shadow of a Badge: A Spiritual Memoir'.
"The white mist then began to take shape. It moved and swirled in patterns of spectacular white light. All at once, the mist took full shape and I saw what appeared to be angels. There were angels standing in the open area to the left of the crash site," the Daily Mail quoted her as writing in the book.
"There were hundreds of them standing in columns. There was a field of angels emerging from the realms of the mist. They were Archangels with their wings arched up toward the sky.
"And I didn't say anything to the guys because you can imagine if I would have said, 'I just saw angels on the crash site,' they'd have called the office and they'd have said, 'She lost her mind and tell her to go home'," she wrote.
But she added that she saw more than just the shapes inside the mist. She, and two men with her, spotted a Bible from the plane that had been barely singed.
"All of a sudden this huge wind came out of nowhere and flipped that Bible open and I remember it flipped open to Psalm 23, "The Lord is my shepherd..." she told CBS Pittsburgh.
"The biggest thing for me is that that there were no bodies. I'm used to crime scenes but this one blew me out of the water. It just looked like the ground had swallowed up' the plane," she said.
Leonardi, now 56, kept the angel vision to herself for two years but as her PTSD began to take control, she told close friends what she had seen.
Kenneth McCabe, her former supervisor, said he had no reason to doubt her story.
"I believe her. I know she believes 100 per cent that's what she saw. I know she's a sane person so I'm not going to discount what she says she saw," he said.
He agreed that the crash site was different than any other scene he had witnessed.
"[Family members] didn't have any closure. They didn't have any bodies to look at. They didn't have anything to look at.
"At least in New York and Washington, there was the devastation but here, except for seeing someone off in the distance, in the woods, looking for things, there was nothing," he added.
The Reverand Ron Lengwin, spokesman for the Roman Catholic Diocese of Pittsburgh, counts Leonardi a personal friend and said he also supported her claims.
"I have no reason to believe that she did not see angels," Lengwin said.
"It's not surprising to me that God could choose to say that he was present there to give comfort to people, and to give comfort to the people who were there to give comfort to other people."
Of Leonardi's claims, the spokesperson for the Families of Flight 93, Lisa Linden, said: "The crash site and sacred ground - now central to the Flight 93 National Memorial - is a place that elicits powerful reactions from those who work at the site and who visit."
Leonardi said that she wanted to write about her vision more than 10 years after the crash is to bring comfort to others affected by the attack or post-traumatic stress disorder.
"The purpose of the book is to tell the story of the angels being there so that other people understand that God was there," she said.
United Airlines Flight 93 was flying from Newark in New Jersey to San Fransisco, California when it was hijacked by four al-Qaeda terrorists as part of the September 11, 2001 attacks.
They overtook the plane 45 minutes after its take-off and turned it around. Its exact target is not known, but it is believed it was flying towards Washington, DC.
But it never reached its intended destination as passengers, who had made phone calls and learned of the other terrorist attacks, attempted to regain control of the aircraft.
During the attempt, the plane crashed into a field in Pennsylvania, killing all 44 passengers on board, including the terrorists. A memorial now stands at the crash site.