Back yards in a half-dozen houses surrounding an Irving lake have dropped about six feet, collapsing decks and toppling fences.

An area about 50 yards long and 10 yards wide collapsed about midnight Tuesday, dropping back yards along the southern banks of the 130-acre Vilbig Lake (search) on the south side of the Dallas suburb of Irving.

"It's like it imploded from underneath," said Teresa Castro, staring out at the roughly 5-foot drop about 6 feet from her home's foundation. "It's unusual. I've never seen anything like it."

"It looks like we're all going to have a big hole in our back yard for a while," Joe Johnson told The Dallas Morning News for a story in Thursday's editions. Johnson said he had limited hope for insurance coverage.

No one said they heard anything to indicate anything was wrong.

Area resident Jim Ferguson lost his 16-by-16-foot wood deck and several birdhouses he had up on poles.

"The dog was out, but he apparently had enough sense to stay out of the damage," Ferguson said.

Ferguson, like other residents, did not know what he would do. Some residents said they would have to add several hundred tons of dirt to restore their back yards to the previous height.

"I don't have any experience with something like this," he said. He added his insurance company also was taken by surprise. "This was this first they'd heard of anything like this in Texas."

Lake Vilbig was created between the 1930s and late 1950s from a quarry and excavation company. The homes were built in the mid-1980s.