It’s been two decades since the day that changed America forever.

On Sept. 11, 2001, nearly 3,000 people died after Islamic extremists tied to Al Qaeda hijacked four jetliners and used them as missiles.

NBC 4’s Colleen Marshall and photographer Charles Busby went to New York City 20 years ago to cover the attack on the World Trade Center and the aftermath.

To mark the 20th anniversary, they went back to New York and all this week will share the stories of 9/11 – 20 years later.

COLUMBUS (WCMH) — It’s estimated 500,000 people live in Lower Manhattan. One of them is Joan Mastropaolo. On the morning of Sept. 11, 2001, she went into the World Trade Center and caught a train to her office on the New Jersey side of the Hudson River.

She sat down and had a front-row seat to disaster.

“I could see those towers in my line of sight, clear as day, beautiful view from Jersey City,” Mastropaolo said.

It was 8:46 a.m. American Airlines flight 11 was on a targeted path.

“I never took my eyes off of that plane, and I watched as American Airlines flight 11 got swallowed up into the North Tower,” Mastropaolo said.

“There was this black smoke hemorrhaging from the tower,” she added. “And what I remember so vividly were the screams from my colleagues who had just seen what I had seen.”

Screams of collective shock, but for Mastropaolo, personal panic: her husband was in their apartment in the shadow of the World Trade Center. He had just stepped out of the shower. She made a desperate phone call.

“I said to him, ‘Go to the window, look up,’” she said. “And when he went to the window, I explained to him what I saw, and I said to him, ‘I think we’ve been attacked.’”

Hundreds were already dead. At 9:02 a.m., United Airlines flight 175 passed directly over Mastropaolo’s office.

“It was so loud,” she recalled. “The engines were roaring. That plane flew down towards the Statue of Liberty, he made a sharp turn over the statue. And that at 9:03, it struck the South Tower, and now the world knew. Now my greatest fears were realized. This was indeed an attack.”

She called her husband for a second time.

“He was now frantic,” Mastropaolo said. “He told me that from my apartment window, he saw the explosion on the South Tower. He said everything was shaking and it was like an earthquake.

“And he said he saw things falling and at that moment, I said to him, ‘Get out, go south, go west, do whatever you have to do to get off the island,’” Mastropaolo added.

She lost contact with her husband for seven hours.

When the towers fell, Frank Mastropaolo was trapped between the debris and the Hudson River, until he became part of a massive volunteer boatlift.

“People don’t realize over 500,000 people were evacuated from the island of Manhattan on that morning by boat,” Mastropaolo said. “They got on ferries, they got on private boats.”

But all the smoky ash, the pulverized glass, the toxic debris we breathed in and waded through 20 years ago was at their doorstep. Six days later, the Mastropaolos were allowed to see their apartment.

“I have to say I kind of had a second September 11 because when I opened up my apartment door, the first thing I noticed was all of my windows were blown in,” Mastropaolo said. “Everything I owned was covered with about an inch and a half of dust. Almost nothing was salvageable.”

Her belongings gone, life as she knew it, over.

“This was my home, this was my safety, this was my sanctity,” Mastropaolo said. “My husband and I loved our lives here, and we were never going to give in to the evil that had happened here on that day. We knew that we had to come back. Frankly, it was never even a decision. We knew we were going to come back. It was much bigger than us.”

She now serves on the board of the 9/11 Tribute Museum, staffed by survivors, family members, and first responders who even give walking tours of the World Trade Center neighborhood.

It’s a neighborhood Mastropaolo will always call home.

“I’m alive, and I get to share my story,” she said. “There are a lot of people who don’t, and so one of the major reasons why I volunteer at the tribute museum and why I’m so passionate about doing this is because the one thing I can do is I can give a voice to the 2,753 people that, on the morning of September 11, went to work and never went home.”

Mastropaolo is one of the survivors who help operate the 9/11 Family Tribute Museum, which has been hit hard financially by the COVID-19 pandemic. If you would like to help support the museum, click here.