A fire at a US nuclear weapons site in South Carolina triggers an emergency and an air and rail shutdown

A fire broke out in a single room at the Savannah River National Laboratory near Aiken on Wednesday evening. Officials confirmed an "unfiltered ground-level radiological release" and declared a Site Area Emergency — ranked second in a three-tier emergency classification system — at 5:39pm local time. A hospital treated one employee for minor injuries. The fire was put out and the emergency declared over by 9:45pm, after checks found no detectable contamination outside the affected facility.

Citing a US government "nuclear incident," the FAA imposed a temporary flight restriction, while rail, river and road traffic near the site were also halted.

Officials confirmed no off-site contamination, but nuclear safety expert Edwin Lyman warned that fires involving radioactive material require "extreme precautions" due to the risk of public exposure.

The Savannah River Site, which still produces tritium for nuclear weapons today, employs a combined workforce of more than 13,000 contractors and federal employees across its 310-square-mile complex.