CHARLOTTE, N.C. -- Flames roared through a south Charlotte house Tuesday morning, leaving a family homeless and two firefighters grateful to escape from the collapsing structure.

Battalion Chief Lance Foulk and Capt. Tom Billig with the Charlotte Fire Department survived a scary moment. While on the second level of the home on the 11000 block of Thornhill Club Drive, the floor beneath their feet gave way.

"The floor started to feel a little spongy and just about that time it started going out from underneath us," said Capt. Billig, speaking exclusively to NewsChannel 36.

What we could see from Airstar 36 looked just as scary to neighbors on the ground.

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Heavy smoke and fast-spreading flames were consuming the Thornhill subdivision home. Just when you figure the situation couldn't get worse, neighbors could hear an ominous noise.

"It was like a snapping, cracking sound," said Denio. "Then the guy's radio said two firefighters were inside."

That was the moment when the floor collapsed.

"It was a helpless feeling," said Billig. "Both of us turned to try and get out, but at that point you're basically going along for the ride."

It was Billig’s worst fall in nearly 25 years as a Charlotte firefighter.

"You still get a little bit of panic with something like that," he said. "We are just real fortunate that there wasn't a whole lot of fire where we fell down into."

Buried alive, their training kicked in and they put out a "mayday" call.

"At that point we knocked some sheetrock and found an opening and started climbing over some debris," Billig said.

Both firefighters walked away uninjured.

Neighbors say the woman who lived in the house was out with her baby, walking their dog when the fire started.

By Tuesday evening, fire investigators had not announced the cause of the fire.