Firefighters were able to control a two-alarm blaze late Wednesday inside Stanford University's SLAC National Accelerator Laboratory, a facility that holds the world's longest particle accelerator.
The fire started about 9:45 p.m. in an 8-by-10-foot high-voltage electronic switchboard in the 2500 block of Sand Hill Road, said Division Chief Frank Fraone of the Menlo Park Fire Protection District.
Fire officials believe an electrical failure caused the blaze, sending a large plume of black smoke over Interstate 280, he said.
Smoke blanketed the area for 15 to 20 minutes.
Firefighters used extinguishers to put out the blaze due to the sensitivity of the equipment and de-energize the switchboard.
Only a portion of the building was evacuated because scientists were actively working on experiments, Fraone said.
The center, which opened in 1962, is one of 10 laboratories operated for the U.S. Department of Energy.
The two-mile-long accelerator was designed to study subatomic particles by accelerating electrons to "nearly the speed of light," according to their website.
Six scientists were awarded Nobel prizes for their work in physics at the center.