Wildfire evacuees have set up tents and campers next to Sonoma Raceway, an auto racetrack supplying them with food, water, bathrooms and other necessities, the Associated Press reported.
"It's all the comforts of home if you need to get by in a pinch. The bottom line is we have a hot shower, a bathroom and a bed and blankets," said wildfire evacuee from Sonoma, Eric Morrison.
New deaths confirmed Thursday took the toll to 31, making this the deadliest week of wildfires in California history.
Many of the flames still burned out of control, and the fires grew to more than 300 square miles (777 square kilometres).
Sonoma and Napa counties endured a fourth day of choking smoke while many residents fled to shelters to await word on their homes and loved ones.
A forecast for gusty winds and dry air threatened to fan the fires, which claimed their 29th victim and are fast becoming the deadliest and most destructive in California history.
Many of the flames still burned out of control.