The latest death in the city of Redding comes despite officials saying they were “optimistic” about the fires slowing down and that they were now “gaining ground”.

Shasta County Sheriff Tom Bosenko said a sixth victim had been found at a home engulfed by flames. The victim’s identity has not yet been released.

A total of eight people have died across the state as a result of wildfires – four of them firefighters.

Details of one firefighter, Brian Hughes, who died while trying to stop flames spreading to the south near Yosemite National Park, also emerged on Sunday.

The 33-year-old was struck by a tree while working with a crew removing brush, such as undergrowth and shrubs, from near the front lines of the fire, according to national parks officials.

In Redding, Bret Gouvea, the California Department of Forestry and Fire Protection’s incident commander said officials were now feeling more hopeful.

“We’re feeling a lot more optimistic today as we’re starting to gain some ground rather than being in a defensive mode on this fire all the time,” he said at a news conference, adding that the fire had not grown inside the city since Saturday.

However, Mr Bosenko said his officers were still looking into the whereabouts of seven missing people.

Police in Redding have had 11 reports of missing people, but Sgt Todd Cogle said many of them simply may not have contacted family members.

The fires in the city was set off by a problem with a vehicle about 16km (10m ) west of the city on Monday, last week.

It moved through Shasta and nearby Keswick by Thursday after being fuelled by fast winds and dry vegetation.

At least 517 buildings have been destroyed and a further 135 damaged, according to the latest figures.

Some of the 38,000 who fled their homes remain frustrated as authorities keep evacuated areas closed off while investigations continue.

Redding resident Tim Bollman hiked four miles to check on his home, only to find it had been completely destroyed.