What's next for the Black Hawk sinkhole?

It was just a normal Monday in Black Hawk when some residents got an evening dinner surprise especially when Pennington County Fire Administrator Jerome Harvey showed up.

"It would be described mainly as like a sinkhole, a very large hole," said Harvey. "There's at least two of them. One is approximately 40- by 40-foot and estimated at least 60 feet deep, the other ones approximately 12- by 12-foot and approximately 30 feet deep."

And Meade County Director of Emergency Services Doug Huntrods said they are bringing in a state geological engineer Tuesday to see what's down there.

"So there's different ways they can test with ground-penetrating radar, some magnetic or electronic density where they can perhaps see if there are additional underground chambers or help us map out the size of this one," said Huntrods.

These tests will be able to tell officials if this hole can be filled or not.

And one theory from residents in the neighborhood concerns a past mining operation in the area, which officials are looking into.

"We don't know if this may have been a natural gypsum deposit that has dissolved in these underground cavities so if it was potentially a historical mine shaft," said Huntrods. "Don't know for sure on that."

The Black Hawk fire chief has a warning for anyone crossing over the yellow caution tape to get a closer look: Stop because the area around the hole is still dangerous.