SAN FRANCISCO (AP) — A wind-driven fire continued to scorch thousands of acres 60 miles (97 kilometers) east of San Francisco, prompting residents to flee their homes and the closure of two major freeways near the central California city of Tracy.

The California Department of Forestry and Fire Protection said the fire erupted Saturday afternoon in the grassy hills managed by the Lawrence Livermore National Laboratory, one of the country’s key centers for nuclear weapons science and technology.

Authorities said the research center was not under immediate threat from the blaze, dubbed the Corral Fire, which had devoured some 20 square miles (52 square kilometers) by Sunday afternoon and was only 15% contained.

Nevertheless, authorities ordered some residents to leave the area and set up evacuation centers.

The wildfire presented no threats to any laboratory facilities or operations and the fire had moved away from the site, Lawrence Livermore spokesperson Paul Rhien said in a statement to The Associated Press early Sunday.