Seventeen years ago, Ottawa-native Maxine Williamson was in her office on the 52nd floor of the World Trade Center in New York City when her life -- and the world -- changed forever.

Williamson was getting her day started at the Manhattan law firm where she worked when American Airlines Flight 11 crashed into the North Tower. The plane collided roughly 40 floors above her 52nd-floor office.

“There was this loud crushing noise and I sort of fell back on the floor,” Williamson said of the moment the plane struck the skyscraper. “My colleague flew off of his chair and the building started swaying back and forth.”

The attack killed nearly 3,000 people and is considered the worst terrorist attack in U.S. history.

Williamson, who wrote a book about her experience on 9/11, says she thought about staying put, but ultimately decided against it. A colleague dragged her out of the office where the two descended the stairs to safety.

She still has her key to her floor and her workplace ID, but everything else she owned at her desk -- even her shoes -- were left behind.

Willamson said she had just moved from the 78th floor a month prior to the attack. None of her colleagues from that high up survived.

After escaping the tower, Williamson navigated the chaos and dust that blanketed the area and eventually made it to a makeshift medical area for treatment.

Back home in Canada, her loved ones were convinced of the worst.

“My family didn't hear from me until about five o'clock in the afternoon,” she said. “They assumed that I died.”

Her son was studying at Wilfred Laurier University at the time and Williamson says his friends and classmates came to console him. To this day, the pair makes sure to chat each Sept. 11.

Shortly after 9/11, Williamson moved to Switzerland and eventually back to her hometown of Ottawa. She hasn’t been back to New York since moving away from the city 17 years ago.

“I started to live my life differently because I got a second chance at life,” she said.

The United States spent much of Tuesday mourning the attacks, with ceremonies across the country. U.S. President Donald Trump marked the occasion at a memorial service in Pennsylvania, where one of the 9/11 hijacked planes, United Airlines Flight 93, crashed into a field as passengers tried to take back control.

With a report from CTV Ottawa