Watch Rachael Bravely Walk Into a Burning Building: "I Had a Straight-Up Panic Attack"

Talk about one SERIOUSLY fierce woman!

Here's something you might not know: Our Rachael sits on the board of Denis Leary's Leary Firefighters Foundation to fund equipment, education, training and more for firefighters all across the country.

Even cooler: She's the first and only woman to do so!

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But while she's donated plenty of money to the organization, she decided to do one better — to actually become a firefighter for a day.

She participated in four challenges, including running up the staircases of burning buildings and getting down into "subway" tunnels on a rescue mission. But one of her fiercest moves? Walking straight into a burning building to help put out a fire.

THE HIGH-RISE CHALLENGE
OBJECTIVE: EXTINGUISH FIRE ON AN UPPER STORY

"This is what we call our high-rise scenario," Captain Paul Nugent explains. "We're simulating a fire in a high-rise building. We have a fire on the 42nd floor, with people trapped. We have to get water up, put out the main body of fire and go rescue people."

Lieutenant Mike Beehler adds, "This high-rise rotation is very taxing on the body. It's demanding, it's very physical, you have to work as a team. If you don't work as a team, you're not going to succeed."

And even though Captain Nugent called it a "Hollywood fire," it was still real, hot, dangerous fire all the same, which is why he instructed them all to crawl until he tapped them on the shoulder -- a signal that they were safe to stand up again.

MORE: Rachael Steps Into Live Fire to Help Friend Denis Leary Raise Money for Fire Departments at 2nd FDNY Firefighter Challenge Event

But even that couldn't prepare them for what was ahead.

“We walked into a room that had a fire… it started to come across the ceiling,” says Chef Anne Burrell, who crawled with Rachael through pitch-black smoke to get to the hose to put out the fire.

"You're there with the hose and they say, 'Big circles! Big circles!'" continues Anne "[It] seems really easy until you start to do it, and you're like, 'Oh, my god, big circles! Is this thing out yet?' Everything about it is physically demanding."

But they did it — even as the heat got so intense, it seemed like Rachael might pass out.

“As she was coming out, it looked like she might have been a little overheated,” says Lieutenant Beehler.

The fireman asked Rachael if she wanted to go back inside, but she immediately answered, "No, no, I can't."

Once she was outside, she told the trainers waiting for her, "I had a straight-up panic attack."

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(And when you watch Rachael and Anne in the video above, you'll understand why.)

“This is actually very normal, especially on a hot day like today,” explains Beehler.

“What firefighters go through is intense,” says Rach, who felt better after finally sitting down and getting lots of water.

Learn more about Denis' Leary Firefighters Foundation here.