The so-called Felicia Fire was reported around 1 p.m. on the west side of Lake Piru, according to Cal Fire. Evacuations were issued for the Lake Piru Recreation area, including Dominguez Canyon.
Later in the evening, the Ventura County Fire Department reported forward progress of the blaze had been stopped. Containment is at 14%.
"Approximately 500 firefighters are assigned to the incident with crews working throughout the night on increasing containment and continuing structure protection," the fire department wrote on X.
Fire officials first estimated the blaze to be between 20-40 acres, but it was later mapped at 292 acres by 5 p.m.
Firefighters battled the flames from the air and on the ground. No structures are currently threatened.
The cause of the fire is unknown.
The fire erupted as red flag warnings were in effect for parts of Southern California amid extremely hot and dry conditions.