WINDSOR TERRACE — New Yorkers still remember where they were and what they were doing on the morning of Sept. 11 two decades ago.

Susan Fiorentino was sitting in her classroom at St. Ann School in Dongan Hills, S.I., that day. Her father was a New York Police Department at the time and went down to ground zero following the attacks.

“I knew my dad worked for important people in the city and that he was a cop. But my 10-year-old mind didn’t know that he worked for the Chief of Detectives or where he was,” said Fiorentino, 30, who is now heavily involved with the Tunnel to Towers Foundation and is a founding member of its Young Professionals Network.

Fiorentino recalls parents picking up their children from the school, which was located down the block from her family’s home.

“I kind of only remember up to leaving school and my dad coming home at some point — though I don’t remember if it was late that night or the next day,” Fiorentino said. “We had an outside basement entrance, and he was covered in God only knows what, [he] changed his clothes, and showered.”

In the year leading up to the 20th anniversary, Fiorentino decided to write down her thoughts and experiences as a child of a 9/11 first responder — focusing on how that day shaped her into the person she is today.

She soon realized she might not be the only one who needed an outlet to share perspectives as children of first responders.

“You always hear about the spouses, siblings, survivors,” Fiorentino said, “but you never hear from the children.”

“Self-doubt crept in,” she continued. “I was like, ‘Is anyone going to want to read this? Is this going to be anything?’ ”

Through the encouragement of her family and friends, Fiorentino decided to use social media and word of mouth to launch her project in August 2020. More than 50 people contacted her, wanting to participate.

“I appreciate all the people contributing because I know it is something hard to write about and to be honest about,” Fiorentino said.

One of those contributors is Caitlyn McIntyre, whose father, Port Authority Police Officer Donald James McIntyre, died in the line of duty on Sept. 11. She was five years old when the attacks on the World Trade Center occurred.

McIntyre said she wanted to contribute to the book to honor her father and create a legacy by which he could be remembered.

“He is truly a hero, and I will forever be inspired by him,” McIntyre said.

“As the 20th anniversary approaches, I hope that people are inspired by the stories of our lives and continue to share the memories of our loved ones so they will never be forgotten.”

Natalie McHale, another contributor to the book, was on the fence about sharing her story.

“People think about it [9/11] one day a year on the anniversary,” McHale said about why it was important to share her story prior to the 20th anniversary. “I think about it every single day [because] I have no choice.”

“It’s weird to see 20 years later how it’s this historical event,” she continued, “but this isn’t history. We’re living it.”

“We’re like the mouthpieces of those who survived, and I feel like it’s kind of my diligence now to start stepping up and making sure people don’t forget,” she added.

McHale’s father, Port Authority Police Detective Thomas McHale, responded to the first World Trade Center bombing, which occurred in 1993, and went back to ground zero eight years later, clearing out rubble every day in the months that followed.

“I’ve never really openly spoken about it [9/11] because I’ve always felt like I’ve never had the right to speak about it because my dad survived,” said McHale, who was 9 years old in 2001. “So many people weren’t as fortunate.”

“I’m so grateful for what I have, but I still feel that guilt,” she continued, adding that she now has a stronger relationship with her father.

McHale, who has also felt angry about the ways 9/11 affected her and her family for more than half her life, said she not only was able to express her emotions through this project but also found a new family with whom she has built lifelong bonds.

“It was so cathartic to actually talk to somebody who understands,” McHale said. “In 18 post-9/11 years, I’ve never been able to connect with somebody on how I’m feeling about this because everyone that I’m close to lost loved ones.”

“On the flip side, as negative as the day is, I realized we’re so strong,” she continued. “I’m an extremely strong person, and I know there’s nothing that can happen that will knock me down after experiencing 9/11.”

All the proceeds from Fiorentino’s self-published book, “We Will Never Forget: The Stories of Children of 9/11 First Responders,” will go to the Tunnel to Towers Foundation to support a new program that helps families affected by 9/11-related illnesses.

“I hope the public realizes that kids of 9/11 first-responder parents are real people and are still struggling 20 years later,” Fiorentino said. “This kind of puts it into reality that someone’s parents risked their lives to save strangers. Some of them didn’t make it out, some of them died years later, some are still struggling — and their families were also impacted.”

“This book paints a picture of what we all experienced that day,” Fiorentino continued, “but we all had different outcomes and different childhoods and adulthoods from it.”