The two fires cover an area larger than the Carr Fire that damaged parts of Redding last week.
No other details about the death were made public.
Along the northern edge of the fire, California Highway Patrol officers and other law enforcement were canvassing French Gulch, urging people who defied original evacuation orders to leave as fire activity picked up.
"In past decades, we may have seen a fire that we're seeing now (such as the Carr Fire), in August or September", CalFire Director Ken Pimlott said during a press conference earlier this week. In addition to the Shasta declaration, Brown's office said FEMA was considering requests for disaster declarations for Lake, Mendocino and Napa counties "on an expedited basis".
California fire officials said Saturday that the Ranch and River fires of the Mendocino Complex, burning near Ukiah and Clear Lake, grew to nearly a combined 250 square miles (201,000 acres).More news: Lions Crusaders Super Rugby Jet Lag
The National Weather Service issued red flag warnings of critical fire weather conditions through Saturday night, expecting a series of dry low-pressure systems passing through the region to push winds as high as 35 miles per hour.
The 206-square-mile (533-square-kilometer) Carr Fire 100 miles south of the OR border was 39 percent contained after destroying 1,060 homes and many other structures.
In his request to President Donald Trump, Brown said the Carr Fire ranked as California's sixth most destructive, having destroyed more than 131,000 acres at the time of writing. In all, they have destroyed hundreds of homes, killed eight people - including four firefighters- and shut down Yosemite National Park.
"These kinds of awful situations bring people together, regardless of the lesser kind of ideologies and partisan considerations", Brown told a news conference Saturday.
Two firefighters have been killed there since a fire erupted just west of Yosemite in the Sierra National Forest.More news: Match Between Woods and Mickelson Set for Thanksgiving Weekend
The National Weather Service has issued warnings for critical fire weather conditions Friday and Saturday as a series of dry low-pressure systems pass through the region, bringing gusts up to 35 miles per hour (56 kph) in the afternoon.
The fire had reached into remote areas of the country's third-oldest national park.
The scorched land figure is expected to rise when the California Department of Forestry and Fire Protection (Cal Fire) issues an update on Saturday night, spokeswoman Tricia Austin said.
The fire, which is almost twice the size of Sacramento, was only partially contained after more than a week.
"The Mendocino Complex fire remains a dynamic and rapidly changing challenge for firefighters, with additional evacuation orders issued on Saturday and thousands of structures remaining threatened by the massive wildfire".More news: Venus Williams tops Watson at Silicon Valley…
There are 14,000 firefighters from California and other states fighting the blazes.