NEW YORK (CBS This Morning) — From 100 yards away, Detective Tina Guerrero fires her Remington 700 M24 rifle, consistently hitting her target.

How good a shot is she?

“I would say I’m pretty good,” she replied.

“I’ve heard you say that ESU is like a big boys’ playground and you wanted to play in it?” asked CBS This Morning’s Norah O’Donnell.

“Yeah. The challenge of just being able to go out there and do all the things that all these guys were doing was something that I wanted to do,” Guerrero said. “I did feel that I had to prove myself, as other women do – and other men do, too.”

The men and women of the Emergency Service Unit endure rigorous training to respond to everything from search-and-rescues to hazmat situations and terrorist attacks.

“When I tried out for the team, I was very intimidated,” Guerrero said. “But I said, you know, ‘Go out there and do the best you can.’ And I did. And I remember getting a phone call from one of the other guys that I work with. And he said, ‘Listen, for what it’s worth, you did well.'”

Well enough to trade in her undercover work in the vice squad for scuba gear and a 50-pound vest.

As a member of ESU, Detective Guerrero has to prepare for any scenario, including suicidal jumpers.

O’Donnell joined the team on a training exercise, climbing nearly 280 feet to the top of the Brooklyn Bridge.

The team looks out for each other as they climb the nearly 6,000 foot suspension bridge that connects Manhattan and Brooklyn, using carabineers to harness themselves so that they’re always tied in.

Detective Guerrero’s husband is also in ESU, though the duo rarely work together.

The mother of three works overnights to spend more time with their children, though she misses a lot of their activities.

“And you put your life on the line, all the time,” said O’Donnell. “Why? Why do you do it?”

“I do it because I just love being out there,” Guerrero said, “I try not to think about, you know, the dangers of it. There’s not a night goes by that the guys I work with, I know that they’re looking out for me, as I do the same for them.”

Guerrero reflected on her journey to the NYPD’s version of SEAL Team Six, where she admits there were some men in the unit who said, “I don’t think this woman can do it.”

“Yeah. I believe when I first came into the unit, that I proved a few people wrong!” she laughed. “I definitely believe that. They’re retired now, though.”

O’Donnell asked, “And how did you disprove the doubters? Because this is a really rigorous job.”

“How did I disprove them? I’m still here. I’m still doing it.”

“Tougher than ever?”

“I love it. I’m out on patrol every night. Wouldn’t change it for the world.”

Those days that do change the world tend to hit her team hard. On 9/11, the NYPD lost 23 officers – 14 were in ESU.

Guerrero said she was supposed to be downtown on 9/11. “I was just coming back from maternity and I was under the impression I was supposed to go to the field that day. And actually, I was supposed to go to the truck,” she said. “I know if I would have went to Truck 7 in Brooklyn, there’s a good chance that I would have been in the towers. A good chance.”

O’Donnell asked, “What does service mean to you?”

“Service is to be there. To be there. To be there to help people, you know, the great people of the city To serve the city is, I tell you, it’s really important to me.”

“You do it because you love it, but it ain’t easy. It’s hard hours, time away from your family, and you risk your life every day,” O’Donnell said. “But it’s worth it?”

“Well worth it. Well worth it.”