Updated at 5:40 p.m.
The Jurupa Valley fire in Riverside County was 85 percent contained as of 4:17 p.m., NBC-LA reported.
A 1-square-mile area from Pacific Avenue to Mission Boulevard and Riverview Drive to 42nd Street are under mandatory evacuation orders, officials said, according to NBC-LA.
The fire has destroyed four homes, 11 outbuildings, three motorhomes and 40 vehicles, most of which were under repair or salvaged, the LA Times reported. Multiple power lines were also reported down.
--With contributions from KPCC's Jessica Hamlin
Southern California firefighters aggressively attacked small but potentially dangerous blazes Tuesday as gusty Santa Ana winds swept the region and humidity levels plunged to vegetation-withering single-digit levels.
The whipping winds brought the threat of embers igniting new fires downwind as a large house burned in the Chatsworth area of Los Angeles and two fires to the east in Riverside County.
The Santa Anas, generated by strong surface high pressure anchored over the Great Basin, a huge area of watersheds that spread over California and five neighboring Western states, were predicted to strengthen Tuesday night and remain at advisory levels until noon Wednesday. But red-flag warnings for fire danger were expected to remain in effect until Wednesday evening.
In Riverside County, a fire close to homes in Cabazon was contained at 10 acres by 158 firefighters. Two air tankers, a helicopter and three bulldozers were also assigned. In the county's Jurupa Valley area, 90 firefighters attacked a fire burning vegetation, vehicles and small structures in a large storage yard. Multiple power lines were reported down in the area.
Winds brought down a tree on a school in San Bernardino late Monday. Nobody was hurt.
Many fire agencies pre-deployed resources to vulnerable areas in advance of the Santa Anas, which are associated with many of Southern California's worst wildfires. Los Angeles and Pasadena activated parking restrictions in hilly neighborhoods to keep narrow roads open for fire engines.
This story has been updated.