CLOVERDALE, Calif. — A fast-moving wildfire prompted the evacuations of 300 homes in the Santa Cruz Mountains, while fire crews continued to battle a blaze burning close to a massive geothermal power producing facility in Sonoma County, officials said Monday.

The blaze that started Monday on the southern edge of Santa Clara County quickly spread to 500 acres, threatening radio and television antennas, said California Department of Forestry and Fire Protection spokeswoman Stephanie Stuehler.

A blaze that erupted amid hot, dry conditions and gusty winds in Sonoma County north of San Francisco forced the temporary evacuation of one of its 14 geothermal plants.

Brett Kerr, a spokesman for Calpine, which operates The Geysers geothermal complex, said evacuated employees were allowed to return to the plant, which started operating later Monday.

All employees were safe and accounted for and the flow of electricity from the facility was not disrupted, he said.

“Our remaining plants at the Geysers continue to operate normally and our team is constantly assessing the situation and will take all steps necessary to ensure the safety of employees and the preservation of our facilities,” Kerr said in an email.

The California Department of Forestry and Fire Protection said the blaze near the small city Cloverdale has charred about 1,500 acres, or more than 2 square miles of timber and dry brush.

Fire spokesman Daniel Berlant said Monday that the fire also burned on plant property, but he did not know how close to the infrastructure.

The Geysers are located in the Mayacamas Mountains and are naturally occurring steam field reservoirs below the earth’s surface. They are harnessed by Calpine to make renewable energy for homes and businesses across Northern California, according to the company web site.

The site says The Geysers, spreading 45 square miles along the Sonoma and Lake County border, is the largest complex of geothermal power plants in the world. Calpine owns and operates the 14 power plants at The Geysers, providing power for the equivalent of 725,000 homes, according to the site.

The Geysers supplies electricity to California’s Sonoma, Lake and Mendocino counties, plus a portion of the power needs for Marin and Napa counties.

About 90 residents from 36 homes near the fire were under evacuation orders or advisories Monday.

The cause of the fire was under investigation as firefighters battling the blaze Monday in steep terrain braced for another day of temperatures in the high 90s and strong winds. Authorities said the fire was 20 percent contained.