The Federal Aviation Administration imposed temporary flight restrictions over the Department of Energy’s Savannah River Site in South Carolina on Wednesday after a fire at the Savannah River National Laboratory triggered an emergency response at the nuclear complex.

The FAA notice classified the situation as a “US Government Nuclear Incident” and restricted flights within a 15-nautical-mile radius of the site, extending from the ground to 10,000 feet. The restriction was scheduled to remain in effect until early Friday morning.

Savannah River Site officials declared a Site Area Emergency at approximately 5:39 p.m. Wednesday after a fire was reported in a single room at the Savannah River National Laboratory near Aiken, South Carolina. The blaze was extinguished, and officials subsequently terminated the emergency declaration after determining that no contamination had been detected outside the affected facility.

Site officials told local station WRDW that the incident involved an “unfiltered ground-level radiological release.” The nature and quantity of any radioactive material released have not been publicly established, and officials reported no indication of consequences beyond the site’s boundaries.

Employees in the affected laboratory section, known as Area A, sheltered behind barricades for approximately 30 minutes before being permitted to leave, according to WRDW. Other employees who were not involved in emergency response or shutdown operations were also instructed to shelter in place as a precaution.

The response included temporarily closing site entrances to incoming traffic and restricting rail, river, and air traffic in the surrounding area. The FAA’s flight restrictions extended beyond the immediate facility, covering a 15-nautical-mile radius and altitudes up to 10,000 feet.

According to Reuters, one employee sustained minor injuries and was taken to a hospital. Officials have not disclosed what caused the fire or provided a detailed accounting of the damage or the reported release.

By 9:45 p.m. Wednesday, officials had terminated the Site Area Emergency and lifted protective actions. Radiation surveys detected no contamination outside the affected facility, and site barricades reopened. Employees scheduled to work Thursday were instructed to report as usual.

The Savannah River Site covers approximately 310 square miles along the South Carolina-Georgia border. Established in the 1950s during the Cold War, the federal complex produced plutonium and tritium for nuclear weapons. Its current missions include nuclear materials management, environmental cleanup, and research.

The Savannah River National Laboratory operates within the complex and conducts research involving nuclear materials and related technologies.

Although officials have reported no detectable contamination outside the affected facility, questions remain about the fire’s cause, the extent of any damage, and the details of the reported radiological release. The emergency declaration has ended, but the incident has drawn attention to the precautions required when fires or other emergencies occur at facilities that handle radioactive materials.