Three more radioactive nests have been discovered since July 3, when the first nest was found, according to the New York Times.

Personnel monitoring radiation levels at Savannah River Site, a facility in South Carolina that once produced parts for nuclear weapons, found a radioactive wasp nest in July. While this might sound like the start of a science fiction horror movie, officials say it does not present a danger to the public.

Four radioactive wasp nests may indicate previously undetected environmental contamination at the decades-old Savannah River Site. Here’s what to know.