A Metro East middle school is on unsteady ground.

Officials at Wolf Branch Middle School said the ground beneath parts of the school is shifting. The movement has resulted in the closure of certain parts of the school as experts investigate the cause.

Wolf Branch School was built in Swansea in 2002, but the cracks didn't show up til just weeks ago

"We started noticing some of the floor tiles starting to buckle," said Superintendent Scott Harres. "We started to notice the cracks were getting bigger. And we noticed not only did we have issues with the floor but in some areas we had issues with the wall."

After inspectors with the Department of Natural Resources saw the cracks over the weekend, they asked the school to close off the gym and cafeteria for further inspection.

"We're going to utilize the hallways outside the cafeteria which has been deemed safe. We're fortunate now that the weather is nice and they can utilize outside," said Harres, adding the closures will have minimal interference with student schedules.

Harres said inspectors have one working theory about why this is happening.

"[There's] lot of underground mines," Harres said. "Unfortunately, the possibility of them shifting becomes a real possibility and they're thinking that's where we are."

"We do have a lot of mine subsidence in the area," said Jim Loyet, parent of a child who attends the school. "The neighborhood behind the middle school is under mines as well. I live in a subdivision where there's mine subsidence as well so it's not shocking."

The superintendent said he still has no idea how much this could cost or how long it will take to fix. But federal grant money may be available to help with emergency costs. If more money is needed down the road, Harres said the school district may have to pay.

Investigators with DNR will be back at the school Tuesday to conduct more testing.