The California Department of Forestry and Fire Protection, which uses acres to describe fire size, said the blaze had blackened almost 206 square miles (533 square kilometers).
Last week, Brown declared a state of emergency in Shasta, Lake, Mendocino, Napa, Riverside and Mariposa counties and secured federal aid to further support those communities, which are impacted by the the state's largest fire - the Carr Fire.
As an army of firefighters battled 17 large wildfires burning across California, the focus on Saturday was a pair of blazes burning on either side of Clear Lake, about 100 miles north of San Francisco. An eighth fire-related death occurred in the Ferguson Fire, east of San Jose, when Capt. Brian Hughes of the Arrowhead Interagency Hotshot Crew was killed.
Dykema says the whirl started when hot air from the exceptionally hot fire rose and twisted tightly, creating a powerful tornado of flames and wind.
Firefighters ride in the back of a pickup truck while battling the Ranch Fire on New Long Valley Rd near Clearlake Oaks, California.
The fire continues to spread into the Mendocino National Forest and crews are scouting for opportunities ahead of the active fire's edge.
"Tragedies bring people together", he added.
Gov. Jerry Brown Saturday inspected Redding neighborhoods wiped out by the Carr Fire and called on President Donald Trump to help California fight and recover from another devastating wildfire season.
Oil prices rally on expectation that inventories will drop
West Texas Intermediate ( WTI) crude futures were at $68.70 per barrel at 0847 GMT, down 26 cents from their last settlement. Additionally, he said, USA monthly figures for production fell in May, suggesting output may be curbed later in the year.
The River Fire is 35,278 acres and 50 percent contained.
A spokesperson for the California Department of Forestry and Fire Protection, or Cal Fire, told SFGate she is unaware of any water shortages at the Carr or Mendocino Complex fires, the worst fire zones in the state.
Two other blazes collectively called the Mendocino Complex burned in Mendocino, Lake and Colusa counties, about 90 miles north of San Francisco. They have forced the evacuation of more than 20,000 residents and destroyed more than 100 structures.
Both areas remained under a "red flag warning" issued by the National Weather Service for strong winds, low relative humidity and temperatures topping 32 degrees Celsius, all conditions that can drive the growth of wildfires.
The fire has also razed more than 1,600 buildings, including some 1,000 homes, making it the sixth most destructive blaze in the history of the fire-prone western state, state officials say.
The declaration for Shasta County will increase residents' eligibility for programs and support in areas such as housing, employment and medical services and provide financial assistance to affected governments dealing with emergency response and recovery costs.
Meteorologist Steve Anderson said wind gusts could reach 25 miles per hour (40 kph) during the day Sunday.
A structure burns out of control in the River Fire (Mendocino Complex) in Lakeport, California, U.S. July 31, 2018. The whirl uprooted trees and tore roofs from homes, Dykema said.