A wildfire that erupted in Northern California forced evacuations as it threatened about 500 homes and other buildings on Tuesday, authorities said.

The Rices Fire erupted near the Yuba River in Nevada County at around 2pm local time and had spread to more than 500 acres (202 hectares) by nightfall, said Unit Chief Brian Estes, of the California Department of Forestry and Fire Protection.

The flames also threatened power lines, water delivery systems and a state park, he said.

California WildfireFlames from the Rices Fire burn near a home along the Troost Trail in rural North San Juan, California (Elias Funez/The Union/AP)

The rural area is in the Sierra Nevada, north-east of Sacramento and about halfway between the state Capitol and the Nevada border.

Authorities earlier said the fire began with a burning building and the flames spread to nearby dry vegetation.

At an evening news conference, however, Mr Estes said he could not confirm reports that some buildings had been destroyed.

About 350 homes and other buildings were under evacuation orders, county Sheriff Shannan Moon said.

Firefighters fought the blaze on the ground and in the air, with aircraft making dozens of drops of water and fire retardant.

California WildfireA helicopter drops water on the mountainside as the Rices Fire burns near French Corral, California (Carlos Avila Gonzalez/San Francisco Chronicle/AP)

The fire was one of several in Northern California that flared on Tuesday as the state sweltered in summer heat, with temperatures in the Rices Fire area hitting up to 36.6C (98F) with low humidity.

A blaze that erupted in San Luis Obispo County on Tuesday morning burned through grass and brush.

It threatened about 50 buildings but no damage or injuries were reported and the blaze was 25% contained, fire officials said.

In Glenn County, a fire that charred more than 300 acres (121 hectares) was 65% contained.

Another fire near Davis, west of Sacramento, was contained without any damage to buildings or injuries after burning 500 acres (202 hectares), authorities said.