A fire at the Savannah River National Laboratory within the sprawling Savannah River Site, located southeast of Augusta, South Carolina, has raised fears of spreading radioactive "contaminants."

The fire on Wednesday at the federal nuclear site, which plays a key role in maintaining America’s nuclear arsenal and processing tritium for warheads and other key components for US nuclear bombs, triggered an emergency response.

The emergency at the nuclear complex was declared at 5:39 p.m. local time (21:39 GMT) and lifted at 9:45 p.m.

Officials at the nuclear complex announced that firefighting operations had concluded, noting that one person sustained minor injuries and no radioactive contaminants were detected outside the facility.

Following the outbreak of the fire, employees were urgently evacuated and relocated to shelters “as a precaution.”

Air, rail, and river traffic were restricted in the area.

Earlier Wednesday, officials had advised residents to stay tuned to local news for updates on any actions they might need to take.

The cause of the fire has not yet been determined.

The Savannah River Site is managed by a pair of private contractors: the laboratory by the Battelle Savannah River Alliance, and the defense site by Savannah River Nuclear Solutions, LLC.

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The facility, which was established in the 1950s, produces tritium and nuclear fuel. It also stores uranium and plutonium used for US nuclear weapons.

The site houses both the national laboratory and a defense complex overseen by the semi-autonomous National Nuclear Security Administration (NNSA) and the US Department of Energy.

The Savannah River Site is also at the heart of the US government’s push to reestablish mass production of US nuclear warheads. Ensuring the nuclear stockpile is one of the NNSA's main missions.

The NNSA recently gave the site the green light to start full-scale construction on a major facility for producing plutonium pits—the explosive cores of modern nuclear weapons—that is expected to cost roughly $23.5 billion, according to trade publication *Exchange Monitor*.

The laboratory area of the site, where the fire occurred, focuses primarily on research in this field.