Sinkhole swallows cars at Corvette Museum in Ky.

BOWLING GREEN, Ky. -- It was a sight to make a classic car lover weep: A gaping sinkhole opened beneath the National Corvette Museum in Kentucky and swallowed eight prized cars like they were toys, piling them in a heap amid loose dirt and concrete fragments.

It happened early Wednesday morning while the attraction dedicated to the classic American sports car was closed to visitors.

"They're all just kind of nose down in the bottom of the hole," said Western Kentucky University engineering professor Matt Dettman, part of a team brought in to assess the damage and stability of the surrounding area.

Six of the cars were owned by the museum and two -- a 1993 ZR-1 Spyder and a 2009 ZR1 Blue Devil -- were on loan from General Motors, said museum spokeswoman Katie Frassinelli.

The other cars damaged were a 1962 black Corvette, a 1984 PPG Pace Car, a 1992 White 1 Millionth Corvette, a 1993 Ruby Red 40th Anniversary Corvette, a 2001 Mallett Hammer Z06 Corvette and a 2009 white 1.5 Millionth Corvette.

"All of these have a unique story behind them," said museum executive director Wendell Strode. "They're special."

An Indiana man donated the 1962 Corvette before his death. He babied it so much he wouldn't drive it in the rain.

"It was just a very immaculate car," Strode said.

The museum has insurance coverage for the damage to the cars and the structure, he said.

The hole opened up about 5:40 a.m. Wednesday, setting off an alarm and a call to the fire department, said Bowling Green city spokeswoman Kim Lancaster.

No injuries were reported. Frassinelli said no one was in the museum at the time.

The museum attracts about 150,000 visitors each year. It's near the factory where the iconic Corvettes are made.

The fire department estimated the hole is about 40 feet across and 25 to 30 feet deep.

The hole opened beneath part of the museum's domed section, an original part of the facility that was completed in 1994. The area will remain closed. The rest of the museum will operate normal hours today, officials said.

The museum said a structural engineering firm determined the perimeter of the domed area is stable.

Pictures of the sinkhole showed a collapsed section of floor with multiple cars visible inside the hole. A few feet away, other Corvettes sat undamaged. Most of the vehicles were later removed from the damaged area, and the museum was contacting their owners.

"It's certainly a sad day here," Strode said.

Visitors trickled into the museum Wednesday, some unaware the main exhibit area was closed. They gazed at the Corvettes on display in the main lobby and shook their heads in amazement that prized Corvettes had been swallowed by the earth.

"That's a whole lot of money just to throw down a hole," said Alida Kriete, who stopped with her family on their way back home in Indiana after a vacation to the Gulf Coast.

Dettman estimated it could take weeks to months to repair the damage. The expense could run into hundreds of thousands of dollars, depending on the extent of any structural damage, he said.

Lancaster said information was still being gathered about what exactly happened, but it appeared to be the first problem of its kind at the property.

Bowling Green sits in the midst of the state's largest karst region -- the Western Pennyroyal area, where many of Kentucky's longest and deepest caves run underground. A karst region displays distinctive surface features, including sinkholes.

Sinkholes are common in the area, but this one was unique, Dettman said.

"One, it's full of Corvettes, and two that it was inside a structure," he said.

Geologists were still trying to determine what caused the sinkhole to open up.

Some of the foundation beneath the dome's main tower appeared to have been undermined, Dettman said, but "the primary foundation system around the perimeter of the structure hasn't been undermined."

Jason Polk, a geography and geology professor at Western Kentucky University, called it an isolated event, and said there was no indication that the sinkhole could spread.

"It's been stable," he said. "We haven't seen any other activity or movement since this morning."

Strode said it appeared at least two of the Corvettes could be saved, but museum officials were still trying to determine the extent of the damage and the value of the eight cars. He didn't know how soon the cars could be recovered.

"Safety will be paramount, but we'll also want to move as fast and as appropriate as we can," he said.

The museum is set to host the 2014 Corvette Caravan in late August, a celebration marking the museum's 20th anniversary. Museum officials expect car clubs from all 50 states and beyond to converge on Bowling Green for the celebration.

The museum had already hired an engineering firm to oversee the repairs, Strode said.

"The Corvette Museum has overcome adversity before and we'll overcome it again," he said. "And we'll have something spectacular to show you back there in short order."

Bowling Green, Ky., is also the lone place where General Motors builds the iconic Corvette.

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Associated Press writers Brett Barrouquere and Rebecca Yonker in Louisville contributed to this report.