UPDATED 04/28/11 6:00 p.m.

HICKORY HILLS, Ill. (CBS) – An explosion knocked an entire home off its foundation Wednesday evening in south suburban Hickory Hills, but the elderly couple inside survived.

The explosion and fire occurred at about 5:30 p.m., according to Hickory Hills police. It was a force strong enough to blow walls out of this house and toss furniture everywhere.

One of the occupants, 82-year-old Virginia Altman, was in fair condition at Christ Hospital. Her husband reportedly was treated and released.

Neighbors said they could feel and hear the explosion block away.

“I felt a big impact, and it was a big swish sound that was like no sound I’ve ever heard before, and all my windows and doors were like the pressure was pushed inward,” said neighbor Cathie Considine.

David Polensky was in the kitchen of his Hickory Hills home when the explosion rattled his walls.

The blast was so loud that he thought an airplane must have crashed at Midway Airport.

But when he and his son walked out of their home on the 9100 block of Barberry Lane, he could see smoke coming from his neighbor’s ranch home across the street. He said that it appeared the explosion occurred in the basement because the home seemed to be rocked off its foundation.

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“The whole front of the house was all blown out, the side of the house was blown off,” he said.”The roof looks like it went up three or four feet and came down.”

Polensky said that a retired couple had lived in the raised ranch home for years and he said he saw the couple walking out of the home appearing uninjured.

“They walked out of the house and survived that thing,” he said. “I’m shocked, you look at that house and it is completely destroyed,” Polensky said.

As for the couple inside, they can consider themselves lucky.

“I think the female in the house self-exited or self-rescued herself; walked out of one of the openings in the wall, and we had assisted the other gentleman out,” said Roberts Park Fire Protection District Chief Fred Vollinger. “There’s no wall there, so I think she just kind of climbed down.”

“She was watching TV, and he was in the kitchen cooking,” Considine said.

The couple told firefighters they could smell a natural gas odor after the blast.

Their daughter-in-law arrived to see the damage left behind. She is grateful they’ll be OK.

“I didn’t know anybody survived it. I’m amazed,” said the daughter-in-law, Mary Altman. “I’m just still concerned about them.”

The couple was taken to the hospital to be checked out. Afterward, Nicor crews worked to make sure the gas nearby was off.

The couple’s insurance agent surveyed the damage Thursday and couldn’t believe they survived.

“It’s a miracle,” State Farm agent Joanna Kierys said.

The Sun-Times Media Wire contributed to this report.