(UPDATE Aug. 4, 8 A.M.) Officials with the Riverside Fire Department have confirmed the Apple Fire was caused by a malfunctioning diesel vehicle.
State fire officials say the vehicle's exhaust system spewed burning carbon Friday in Cherry Valley in Riverside County, although it hasn't been found.
The blaze, being called the Apple Fire, is raging for a fourth day and has burned one home.
As of Monday, the wildfire had burned nearly 27,000 acres and was only 7% contained, according to the California Department of Forestry and Fire Protection.
(UPDATE 10:15 P.M.) The fire is 900 acres and 0% contained.
A brush fire near Cherry Valley triggered a mandatory evacuation order after burning through at least 700 acres Friday evening.
The so-called "Apple Fire" was reported at 4:55 p.m. in an area north of Riverside County. An estimated 250 firefighters responded to the blaze as it burned in several spots along Oak Glen Road.
Officials said the fire is 0% contained as of 8:15 p.m.
Mandatory evacuation orders were in place in the Cherry Valley area, for residents north of Dutton Street, east of Oak Glen Road and south of the Riverside County line.
The evacuation center is at Beaumont High School, located at 39139 Cherry Valley Blvd. Animals can also be taken to that location.