By CBSLA Staff

CHERRY VALLEY (CBSLA) — Fire officials Monday said the Apple Fire, which has burned more than 26,000 acres, was caused by a malfunctioning vehicle.

A helicopter drops water on flames during the Apple Fire in Banning Aug. 1. (Photo by Josh Edelson/AFP-Getty)

According to the Riverside County Fire Department, a diesel-fueled vehicle emitting burning carbon from the exhaust system was driving down Oak Glen Road, sparking a number of small fires Friday at about 4:55 p.m.

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Initial on scene fire crews responded to reports of multiple spot fires burning alongside Oak Glen Road. By Saturday afternoon, the fire had burned more than 4,000 acres, destroyed one home and two out buildings — forcing widespread evacuations of about 7,800 people.

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As of Monday, the blaze had grown to 26,450 acres and was still actively burning due to record-low moisture content in the vegetation, high temperatures and low relative humidity.

Evacuations remained in place in both Riverside and San Bernardino counties.

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Cal Fire peace officers have asked that anyone with information about the vehicle or who might have seen a vehicle which appeared to have mechanical problems or unusual smoke emitting from it to call 800-633-2836. Anyone who was driving down Oak Glen Road around the time the fires started was also asked to call.