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 been two decades since the 9/11 terrorist attacks that claimed the lives of 2,606 people in the World Trade Center in New York City.

In the hours and days immediately following the attacks, there was a desperate search for survivors.

With the world watching New York City, there were thousands of people who wanted to help, including a group of Jersey City firefighters right across the Hudson River. They wanted to help save lives, and to do so, they were ready to put their own on the line.

They lined up, ready to go – not just underground, but under the Hudson River.

“Somebody might still be alive somewhere,” said firefighter Jim Roemer. “You know, maybe in a pocket somewhere you might be able to reach and get somebody out of this predicament.”

The firefighters volunteered to walk into the path-train tunnel that connects Jersey City to the World Trade Center.

“Somebody could be there and until we find out that they’re not, we’ll keep trying to get them out of there,” said firefighter captain Mark Fallon.

What we were supposed to do was walk from the Jersey City side, hopefully, to be able to get through the tunnel to the NYC side and then check to see if there was anybody that we could rescue, hopefully, or recover, said

Twenty years later, NBC4’s Colleen Marshall met up again with Fallon and finally learned what happened that day, when they walked into the nearly mile-long tunnel.

“It was scary,” Fallon said. “It was dark. I mean, there was some lighting. We had hand lights, you know, flashlights, but still, you know, you walk in shoulder-to-shoulder with some of your best friends and you’re walking through this and you don’t know what’s going to happen.”

The firefighters in the tunnel worried about the structural damage they could see above ground spreading into the tunnel, which it did. The tunnel was blocked and flooded.

The Jersey City firefighters entered the tunnel on Sept. 12, the day after the attacks, but Fallon and his team were at Ground Zero on 9/11, and many days after.

“It was like in a movie,” Fallon said. “There was that gray dust all over everything, all over people, all over cars. They were transporting us back and forth to the scene and because of that, there was a lot of dust up in the air. We were inhaling a lot of dust.”

They were part of a special Jersey City task force, helping on the front line that he wants no one to forget.

“It’s important for them to know what happened to not only people that died, but the people that died afterwards, going over there trying to, you know, dig in on the pile, as they called it, every day, and then developing cancers and things like that,” Fallon said.

Romer died a few years ago, from cancer.

Fallon said he and other firefighters at the site were not wearing masks.

“They said you didn’t have to overlay,” he said. “They said that the air was fine, that the EPA, they were testing it all the time and saying that the air was fine, so didn’t have to worry about it. So nobody did, but obviously, you did have to worry about because they should have had masks on from day one.”

The worry came later, along with the anger and the funerals, but in the hours, days, and weeks after the towers fell, the firefighters worked to rescue and recover.

“It’s just your job,” Fallon said. “It’s what you do. You have to, You can’t just stop, you can’t shut it down.

“Everybody has their job and everybody knows their job and you do your job and then you worry about the injured and the sick and, unfortunately, the deceased when you job is finished.”

Fallon retired a few years ago. Sept. 11 is his wedding anniversary, but he said it’s never been the same since 2001.