Residents who were forced to leave their homes over the weekend when a wildfire broke out near a local explosives and materials testing site in San Joaquin County were allowed to begin returning home Sunday evening, authorities announced.

The Corral fire, which began Saturday afternoon near the Lawrence Livermore National Laboratory Site 300, is burning to the west of Interstate 580. It had grown to 14,168 acres by Sunday night.

The fire is 50% contained, the California Department of Forestry and Fire Protection said.

Feeding on light, dry grass, the blaze moved toward Tracy, a city of about 100,000 east of San Francisco, and triggered mandatory evacuations that were downgraded to warnings at 6 p.m. Sunday.

“Residents are advised to remain vigilant and prepared for potential changes,” San Joaquin County’s office of emergency services said in a notice to residents.

The fire was also considered a threat to the nearby laboratory, which the Environmental Protection Agency describes as a “high-explosives and materials testing site in support of nuclear weapons research,” the Associated Press reported Sunday.

The EPA said operations at the site, which began in the 1950s, “contaminated soil and groundwater with hazardous chemicals,” and long-term cleanup is ongoing.

The fire briefly shut down Interstate 580, but all lanes have since reopened. Local closures remain in place while crews continue to battle the blaze.