Crews worked Tuesday to stabilize and search a collapsed parking garage, but it still wasn't clear what caused the deck to collapse from the fourth floor to the ground level a day earlier.

Remarkably, no injuries were reported and there were no missing people. But rescuers using dogs, listening devices and thermal cameras said they still hadn't finished searching the wreckage.

"At this point, we still haven't found any signs of any victims," Atlanta Fire and Rescue spokesman Bobby Stewart said. "We are going to search every corner, every confined space, every vehicle to make sure no victim is left behind."

The search stalled during the night when the building shifted. It took fire crews several hours to shore up the building enough to continue working. At least 38 cars were caught in the collapse.

"Overnight, I would say we have made very good progress," Atlanta Fire Battalion Chief Steven Woodworth said.

The deck collapsed about lunchtime Monday in the busy commercial district of Midtown. More than 50 firefighters rushed to the scene and the bottom level was a "huge mess of vehicles and concrete," Fire Chief Kelvin Cochran said.

Shaun Dodson was eating lunch in his truck at the far side of the building when he felt the ground shake and heard a sound like a building "being demolished."

"I ran around, saw a hole and thought the building was collapsing," Dodson said. "I'm eating lunch from now on in my office."

What caused the 7-year-old structure to collapse was not immediately known. Atlanta-based Hardin Construction, the general contractor on the deck, was one of three companies that was working at the Atlanta Botanical Garden when a pedestrian bridge collapsed in December, killing one worker and injuring 18.

Hardin Construction spokeswoman Barkley Russell confirmed the company was the general contractor on the parking deck and surrounding office complex. She said the majority of the deck work was done by subcontractor Metromont Corp., based in Greenville, S.C.

Harry Gleich, vice-president of engineering for Metromont, said he didn't know why the structure failed but said hot weather and weight were not likely factors.

"No investigation has started," he said at a midday news conference Tuesday.

He said the deck was built from prefabricated, precast concrete pieces manufactured at their plants in Greenville, S.C. and Hiram, Ga. The pieces were assembled on site with a "topping slab" of concrete poured on top. He estimated that over 60 percent of U.S. parking garages are built this way.

"As far as I know, they're as safe as any other construction," Gleich said.

The parking deck was last inspected at the time it was built and cleared for occupancy in 2002, said Catherine Woodling, spokeswoman for Atlanta Mayor Shirley Franklin. It has not had any code violations, Woodling said.

Hardin was fined $6,300 earlier this month by the Occupational Safety and Health Administration in the Botanical Garden bridge collapse. The agency's report concluded Hardin and another company placed two support towers too far apart, which may have caused the collapse. The company is appealing.

LIVESHOTS: Atlanta Parking Deck Collapse

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