Strange Sounds Shake Up Clintonville, Wisconsin (Video)

Strange sounds, described as similar to thunder or an earthquake, have been unsettling the residents of Clintonville, Wisconsin for two straight nights. Officials are baffled about the cause, but say the strange noises are for real.

Offering no explanation to worried locals, activities like construction and "fracking" have been investigated. So far, no cause has been found for disturbing the late-night sleep of thousands of people who have flooded 911 with emergency calls, ranging from reporting earthquakes to UFO sightings.

These incidents immediately call to mind the so-called "Strange Sounds" phenomenon which swept the world in January. In those cases, unidentified groaning noises, like those made by earth digging machines, were heard and recorded by hundreds of people all around the globe.

Most cases were found to be the result of a probable widespread hoax perpetrated by pranksters or, in the most extreme explanation, a publicity stunt prior to a sci-fi movie release.

But these latest rumblings have occurred in the dead of night in Clintonville, a small town located about 150 miles from Milwaukee. Calls to 911 have been pouring in and local officials have verified the sounds are real, backing up the reports with seismic data and other physical evidence. What can they be?

Here's how CNN is reporting the story: