Alameda County firefighters have fully contained a vegetation fire at a test facility owned by the Lawrence Livermore National Laboratory on the Alameda County border near Tracy, a laboratory spokeswoman said.
Alameda County firefighters responded at 1:55 p.m., according to fire spokeswoman Aisha Knowles.
It occurred in a ravine off Corral Hollow Road near the Carnegie Vehicular Recreation Area, said Linda Seaver, a spokeswoman for the laboratory.
"We did have some employees who sheltered in place as a precaution, but there was never any threat to the public," Seaver said.
The fire was first reported at just 4 acres, but it quickly grew to 40 acres. It eventually grew to somewhere between 100 and 150 acres, according to Seaver.
Firefighters are in the final stages of putting the fire out, and they're not expecting it to grow any more, Seaver said.
Firefighters from the Livermore-Pleasanton Fire Department and the Tracy Fire Department in San Joaquin County also responded, according to Knowles. Cal Fire is also involved.
The California Highway Patrol has closed a segment of Corral Hollow Road until further notice because of smoky conditions, Seaver said.