A bomb squad is at a South Carolina beach after Hurricane Matthew apparently unearthed old Civil War cannonballs from the sand.

Charleston County Sheriff’s spokesman Maj. Eric Watson said in a news release that the cannonballs were found on Folly Beach on Sunday afternoon, but bomb squad members couldn’t get to it immediately because of the rising tide.

CBS Charleston affiliate WCSC reports that a number of the cannonballs were detonated by the Air Force and a small amount of them would be transported to the nearby Naval Base.

Witnesses reported hearing at least two loud booms and seeing smoke in the area Sunday evening during the detonation of some of the cannonballs.