"I was knocked to the side, I didn't fall down but I was jostled to the side," she said. "Then I heard this almighty screaming sound, a woman screaming the scream of nightmares.
“It's a scream that I can still hear in my head... she walked through the door and her eyes were full of blood."
Brooks was one of the lucky ones, but how many people survived the ordeal in total?
Here is everything you need to know.
How many survivors were there?
It’s hard to determine just how many people survived the 9/11 attacks.
Firstly, the parameters of what constitutes a survival of the event are unclear: does a person who lived only a handful of blocks away constitute a survivor, or a witness?
In terms of direct results of the attacks, more than 6,000 people sustained injuries, while 2,977 people were killed.
Those that were at Ground Zero during the event - and could therefore undoubtedly be labelled as “survivors” - are still living with the effects of what happened 20 years later.
As of August 2013, medical authorities concluded that 1,140 people who worked, lived, or studied in Lower Manhattan at the time of the attack had been diagnosed with cancer as a result of “exposure to toxins at Ground Zero”.
It has also been reported that over 1,400 rescue workers who responded to the scene in the days and months after the attacks have since died, and at least 10 pregnancies were lost as a result of 9/11.
Who is the ‘Dust Lady’?
A total of over 33,000 police officers, firefighters and community members have been treated for injuries and sickness related to the 9/11 attacks in New York City.
Their ailments include respiratory conditions, mental health problems like PTSD and depression, and gastrointestinal conditions.
Among them is Marcy Borders, an American legal assistant who worked on the 81st at the Bank of America located in the World Trade Centre.
A photographer captured an image of Borders, completely covered in dust from the building’s collapse, that led to her becoming known as "The Dust Lady".
Borders was diagnosed with stomach cancer in August 2014, and believed her illness was triggered by the toxic dust she was exposed to following the building’s collapse.
She died a year later in August 2015.
How many people survived above where the planes hit?
No one survived in or above the impact area in the North Tower, and only 18 people escaped from the impact zone of the South Tower after it was struck - no one escaped from the floors above it.
One of the survivors from the South Tower was Brian Clark, a Canadian businessman who also worked on the 84th floor for Euro Broker.
After Flight 175 struck the tower, Clark and seven other employees on his floor started to descend Stairwell A.
They made it to the 81st floor, when they were met by a woman and a man, who warned them there were flames and smoke further down.
Clark and his coworkers debated what to do next, and as the group stood deliberating, a scream for help caught Clark's attention.
While he went to look for the person in need of aid, Clark’s coworkers started to go up the stairs to the roof. That group would all lose their lives that day.
Clark was able to make it out of the South Tower - he even rescued Fuji Bank employee Stanley Praimnath, who was pinned underneath some debris, on his way down - with just four minutes to spare before the building collapsed.
How many survivors were pulled from the rubble?
After the towers collapsed, only 23 individuals in or below the towers escaped from the debris, including 15 rescue workers.
16 individuals survived the collapse of the North Tower; they were all trying to evacuate via stairwell B located in the centre of the building.
One of those was firefighter Jay Jonas, who told The Sun how he, his crew and other survivors were trapped in the stairwell as the building came crashing down around them.
Recalling poking his head out from the rubble, he remembered saying: “Guys, there used to be 106 floors over our heads — now I see sunshine. I think we’re on top of the World Trade Centre”.
“I couldn’t believe what I was seeing. I saw what was left of the facade of the exterior of the World Trade Centre. It was eerie. You could see smoke and a vast rubble field. It looked like we just got bombed.”
Some who found themselves trapped by rubble were able to survive for more than a day; the last survivor removed from the collapse debris was found in the ruins of the North Tower 27 hours after its collapse.
Others were not so lucky, and an unknown number of people who survived the initial collapse, but were buried in air pockets beneath the rubble, could not be rescued in time.
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