UPDATE 10 a.m. Friday - Containment of the Cow Fire has increased to 85%.
CAL FIRE reports the acreage remains at 761.
MILLVILLE, Calif. - CAL FIRE said they determined the cause of the Cow Fire that has burned 761 acres in Millville.
The fire was caused by hot catalytic converter parts that were ejected from a vehicle passing by, CAL FIRE said.
CAL FIRE said a witness gave investigators a description of a vehicle that was running poorly and the vehicle was located in the Palo Cedro area on Monday.
Investigators inspected the vehicle which determined the catalytic converter was not working correctly.
The Cow Fire is currently 65% contained as it broke out around 3:30 p.m. Sunday.