The Poinsettia wild fire spreading across Southern California has prompted the evacuation of the San Onofre nuclear plant.

Southern California Edison said that a dozen employees were evacuated as the fire edged closer to the plant, the Los Angeles Times reports.

The plant is located on the Orange-San Diego county line north of Camp Pendleton. A statement on the plant's website said the evacuation was a "precaution", with 13 non-essential employees moved away from the site.

Tom Palmisano, Southern California Edison (SCE) vice-president and chief nuclear officer, said personnel were dousing vegetation surrounding the site with water as a preventive measure.

"We will continue to monitor the fires near Camp Pendleton and support firefighting efforts. The fires do not pose a safety issue at San Onofre at this time, but we continue to coordinate with regional agencies to ensure we remain appraised of evolving conditions."

San Onofre is currently shut down and due to be decommissioned over the coming months.

The biggest risk of the wild fire is now the city of San Marcos, north of San Diego. Around 21,000 people have been told to evacuate, while around 10,000 in California State University, San Marcos, have been taken to emergency centres.

San Diego County district supervisor Bill Horn told CNN there were now eight fires burning in the region. The fires broke out following a heatwave that saw temperatures rise well above 30C.

Winds caused the brush fire to tear through Carlsbad, destroying several properties and causing power failures in many areas.

The first fire, which broke out at Carlsbad, has burned more than 9,000 acres. The second fire, called Tomahawk, broke out at Camp Pendleton Marine Base and has destroyed around 6,000 acres so far.

Tourists had to be evacuated from Legoland amusement park, while thousands more residents were told to leave the area.

California Fire Captain Mike Mohler told CBS8: "This is a very difficult firefight. This is an urban wildland firefight, so it is definitely more difficult than you would see in a more rural setting."