Janice Brooks had only moved to New York a couple of weeks before 9/11 to begin what she calls “the biggest adventure”, working for a company on the 84th floor of the South Tower of the World Trade Center.
She told the BBC she was in the office when the first plane hit the North Tower. While she was evacuating, the second plane hit with an “almighty thud”.
Brooks said she heard “one of those horror film screams” as a woman was hit by debris. She looked up and saw a “big gaping hole” where her office should have been.
Every year on 11 September, bells ring to commemorate the exact time that each of the four planes crashed, and the exact time the Twin Towers fell.
Each of the six bells is followed by a moment of silence.
This year, a seventh bell was rung to commemorate the thousands who died from diseases including cancer after the attacks.
Illnesses related to dust and smoke from the towers’ collapse have since claimed more than threefold the nearly 3,000 lives lost in the attacks, US health officials say.