A mystery unfolded in Tennessee over the weekend when people reported an unexplained explosion and shaking.

The 911 dispatch center in Montgomery County started getting an influx of concerned calls around 9:50 p.m. Saturday, according to the Clarksville Police Department. Residents from across the county were saying they felt the ground shaking and had heard a “loud explosion.”

But no callers reported any injuries or property damage, police said Sunday.

Several people commented on the police department’s Facebook page on Sunday saying that they too had heard an explosion and felt the ground shaking Saturday night.

“Explosion was so loud and homes shook,” one wrote. “Residents actually came outside to see what had happened.”

“We heard it too in Hilldale,” another user wrote. “Big enough sound that we looked outside and listened for sirens.”

Multiple agencies went out to search for the source of the mysterious shaking and explosion that night, but after two hours, they were unable to find any clues as to what caused it.

Police said nearby Fort Campbell in Kentucky is on a four-day holiday for Labor Day and that it’s unlikely that some type of training or exercise there would explain the reports.

Additionally, the U.S. Geological Survey did not register any earthquakes in Tennessee on Saturday.

Officials in the county seemingly remain stumped about the cause of the commotion and haven’t provided an update on what could have caused it as of Monday.

“Currently, this seems to be some sort of unknown phenomena until someone reports actual damage,” police said.

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