A fire at a lab on a South Carolina site that makes material for nuclear weapons set off an emergency on Wednesday evening, CNN and the Washington Examiner report. The fire was put out. Site officials said no contamination was reported outside the affected building.

The fire broke out at the Savannah River National Laboratory near Aiken, on the Energy Department's Savannah River Site. Officials declared a Site Area Emergency. They ended it later that night, after traffic at all gates resumed, CNN reports.

As a precaution, barricades at site entrances were closed to incoming traffic, the outlets report. Rail, river and air traffic nearby were also limited, CNN says. The Federal Aviation Administration issued a temporary flight restriction that cited a "nuclear incident," the Washington Examiner reports.

Workers in the affected areas were sheltered as a precaution, CNN reports. Lab workers sheltered in place for about 30 minutes, the Washington Examiner says, citing a local station. Earlier, officials had asked nearby residents to follow local news for updates.

The site covers about 310 square miles across Aiken, Allendale and Barnwell counties, the Washington Examiner reports. More than 13,000 contractors and federal workers are employed there, CNN says.

The complex was built in the 1950s to make tritium and plutonium for nuclear weapons, CNN reports. It still makes tritium today. The lab focuses mainly on research rather than large-scale production. The cause of the fire has not been reported.

What we know: A lab fire set off a brief emergency, and officials say no contamination was found outside the facility.
What we don't: What caused the fire, or whether anyone was hurt.