SAN FRANCISCO — Thousands of people were told to leave their homes Sunday as a wildfire burning in thick forest threatened rural communities in far Northern California.

The fire that sparked about 11:30 a.m. Saturday has destroyed four homes and consumed nearly 11 square miles near the towns of Manton, Shingleton, and Viola, fire spokesman Daniel Berlant said. About 3,500 homes across a rural area on the border of Tehama and Shasta counties are threatened. The cause of the fire has not been determined, but officials said it started after a series of lightning strikes in the area.

The Shasta County Sheriff’s Department has declared a State of Emergency for the county, with evacuations expected to continue through Sunday. The fire in an area of thick forests about 170 miles north of Sacramento is one of handful of new fires burning in Northern California.

Elsewhere in the West, fires also continued to rage. In Idaho, about 1,100 firefighters worked to protect some 350 homes in the Featherville area under a mandatory evacuation as the Trinity Ridge Fire continued a slow approach toward the community. In Washington better weather conditions have helped firefighters gain ground on fire that has scorched dozens of homes near Cle Elum, about 75 miles east of Seattle. In Mendocino County, Calif., a wildfire that started Saturday has consumed about 1.5 square miles east of Covelo.  The blaze, which was sparked by lightning, was burning in a remote area of thick timber and rugged terrain.