By GREG BLUESTEIN and DORIE TURNER

ATLANTA (AP) — Part of a six-floor parking deck near downtown Atlanta collapsed Monday, crushing at least 35 cars, with fire officials saying it was miraculous there were no reports of injuries hours after the mass of concrete fell during a busy lunchtime.

Crews were stabilizing the building with timber supports, and firefighters were preparing to search car by car in the evening. The deck “pancaked” from the fourth floor to the first level. More than 50 firefighters rushed to the parking deck around 12:30 p.m. and the bottom level was a “huge mess of vehicles and concrete,” said Fire Chief Kelvin Cochran

“We’re hoping with all our hearts that we don’t find any people inside,” Cochran said at a news conference.

What caused the 7-year-old structure to collapse was not immediately known. 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.

The search of the parking deck was delayed when engineers spotted signs of bolts popping on the other side of the deck, said J.P. Spillane, an Atlanta police official. A handful of welders soon entered to shore up the area. Search dogs were to ready to sniff through the rubble once the building was secure.

“We want to be absolutely sure the building is safe and there is no secondary collapse,” 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.”

Firefighters will tunnel through the debris with listening devices to pick up any noise from possible victims, Cochran said.

If no one is found, he said crews will then do a “more aggressive” search using heavier equipment. The work could continue through the night.

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

There are 1,415 spaces and about 35 were affected, Russell said in a statement.

“We are just thankful at this point there are no reports of injuries,” Russell said.

Russell directed questions about how the deck was designed to Metromont Corp., which did not immediately return a call for comment.

Earlier this month, Hardin was fined $6,300 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.

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 since, Woodling said.

The collapse sent workers in the busy commercial district scurrying to the area.

John Hurlbut, who parks at the deck every day, spotted his Hyundai Sonata just a few feet from the gaping hole.

“I’m very fortunate,” he said. “And I feel everyone is very fortunate. I’m amazed no one was hurt.”

Copyright © 2009 The Associated Press. All rights reserved.