Danger exists inside Dodge Co. mine where boys were located: "It collapses every once in awhile"

DODGE COUNTY -- For many first responders involved in the search for three missing Dodge County boys now safe, Monday, July 11th was the first time they performed a rescue mission inside an abandoned mine/cave.

A culvert with its bottom bars removed is where emergency responders say the three teenage boys likely accessed the Neda mine.

"(The mine) ranged anywhere from spots where you had to squeeze through your belly to squeeze through rocks into very open caverns where you could probably park a car in," said Brian McNulty with the Milwaukee Fire Department.

Video shared by CNN Monday evening shows the moments after the boys were rescued:

McNulty was on the four-person team that found 16-year-old Tate Rose, 16-year-old Zachary Heron and 15-year-old Samuel Lein. McNulty said once the boys entered the culvert, they went down a treacherous path.

"There's a lot of the rock that's unstable. You can see it's just hanging on by pieces. You can see as time goes on, it collapses every once in awhile underneath the ground," McNulty said.

Many in the community said kids often talk about exploring the abandoned mine.

"They're teenagers and they're going to do what a teenager would do to have an adventure," said Austin Mejaki.

Nicholas Palm is one of only a handful who has actually done it.

"In the cave, there's ridges. And if you fall off one of the ridges, you're going to fall into an area that's too deep to get out of," said Palm.

The three boys were found in a large, open area in one of the tunnels. It was pitch black and around 58 degrees.

McNulty said the boys made the right decision to stay in place once they became lost -- instead of trying to navigate their way out. They slept in the mine overnight and were rescued Monday afternoon.

"I think they could have ended up injured if they would have ventured out from there," McNulty said.

The Neda mine is an abandoned iron mine in Dodge County -- the site of the largest bat hibernaculum in the Midwest.

The property was acquired by the University of Wisconsin-Milwaukee in 1976.

At that time, an estimated 75,000 bats were using the mine.

Now, more recent estimates suggest that the population has grown to 150,000 to 200,000. The majority of these are little brown bats.