Arce -- a producer for CNN who lives in Lower Manhattan -- had been trying to get to the World Trade Center after seeing smoke coming from the north tower from her apartment.
"My goal was to get in the building," she recalls.
Arce had just flagged down a photographer -- Jim Huibregtse, who was videotaping his kids' first day at school -- asking if she could borrow his camera, when they "could feel" a shadow fly over them. The shadow, they later learned, was American Airlines Flight 175, which crashed into the south tower.
"They're doing it on purpose!" one of Huibregtse's kids screamed.
"That's when we realized this wasn't an accident," Arce says.
Arce, who was calling in to deliver live reports on the air for CNN, went back with Huibregtse to his apartment near the World Trade Center to use his landline. There, from a penthouse terrace, Huibregtse used a telephoto lens to get a better view.
"We saw these little dots, people jumping from open windows," Arce says. "We were mesmerized; we couldn't comprehend what was happening -- we thought there was a net. Then we saw this person pushing people." They realized there wasn't a net.
By that time, Huibregtse's children wanted to know what the dots were.
"I think it's little birds," Huibregtse said, leading them away from window.
Moments later, the south tower collapsed. "It looked like an accordion," Arce says. "People were still jumping. Then we could hear things hitting his window."
A cloud of debris followed. "It was this strange blizzard," Arce says. "It was like tumbleweeds coming toward us."
Arce stayed in Huibregtse's apartment, continuing to deliver on-air reports after he and his family fled. She eventually left, heading toward Ground Zero with a CNN cameraman. Arce was interviewing a local resident near WTC's Tower 7 when the cameraman tapped her on the shoulder. "It's going to come down," he told her. "We've got to run!"
"It was this odyssey, like being in an action flick," she says. "It didn't feel real."
At sunset, she came upon a parking lot in Battery Park, with cars burning in a "soup" of debris -- "blood, human remains, desks, pictures."
"I remember picking up a girl's resume who had gone to my school," she says.
Arce stayed out until 3 a.m. When she returned to her apartment south of 14th Street, the building was eerily empty. "I think there were 77 units, and not one light was on. Not even the lobby."
As a New Yorker, Arce says, she spent the night thinking about the people whose lives were lost -- and the twin towers themselves. "The iconic center of the city -- to see that destroyed, it will stay with me forever." Every time she crosses the street, catching a glimpse of where the towers stood, she says, "I still can't believe the emptiness in the sky."
Arce, now a senior producer for CNN, has spent the last 10 years trying not to think too much about the Sept. 11 attacks. "I try to avoid gratuitous contact with it," she says. "If I didn't work for CNN, I would try to never think about 9/11 again."
She does, of course. Arce's documentary, "Beyond Bravery: The Women of 9/11," is slated to premiere Thursday, Sept. 8, at 11 p.m. ET, re-airing on Sept. 11 at 8 p.m. ET, on CNN.
The documentary tracks some of the women profiled in the book "Women at Ground Zero," by Susan Hagen. A few of them have moved on to work for Homeland Security, some are helping rebuild Ground Zero, and others are "fighting with the government for medical coverage," Arce says. "It shows that Sept. 11 did not end on 9/11."
She admits that her experience on Sept. 11 has helped her in her war coverage. "When I covered the war in Afghanistan, I thought about [9/11] a lot," she says.
Arce still lives in the same apartment in Lower Manhattan, and she now has a 6-year-old daughter, Luna. But she has yet to have the "9/11 talk" with Luna.
"How do you explain that to a kid, who is going to ask why?" Arce says. "If she asks, 'Could this happen to me?' ... How do you answer, 'Yes'?"
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