Firefighters have made some progress against California's deadliest current wildfire, which had been getting larger, officials say.

The Carr fire is now 20% contained, up from 5% on Sunday when wind and dry conditions were causing it to grow.

It is one of eight major wildfires currently burning in the state.

The fire, in the Shasta County in northern California, has killed six people so far, including two children and their great-grandmother.

Melody Bledsoe, 70, Emily Roberts, five, and James Roberts, four, died when they were caught in its path as they were about to evacuate their home in the town of Redding, about 150 miles (240km) north of Sacramento, on Thursday.

An unidentified fourth body was found in a burnt-out house on Sunday.

Two firefighters also lost their lives on Thursday. Another died battling the Ferguson fire, near Yosemite, on Sunday.

At least eight people have now died from fires in the state.

The Carr fire has already burned nearly 100,000 acres and destroyed more than 720 homes and 240 other buildings. Nearly 200 more buildings have been damaged and 5,000 more are under threat.

The blaze is being fought by nearly 3,400 firefighters with equipment including 330 fire appliances and 17 helicopters.

It began on Monday. On Thursday it became a firestorm, jumping across the Sacramento River.

California department of forestry and fire protection (CalFire) chief Ken Pimlott told reporters they were "seeing fire whirls - literally what can be described as a tornado".

"This fire was whipped up into a whirlwind of activity" by gale-force winds, he said, "uprooting trees, moving vehicles, moving parts of roadways".

A total of 38,000 people have been evacuated from Shasta County. California's Governor Jerry Brown has declared a state of emergency in the area, as well as three others.

US President Donald Trump has approved federal aid for the counties.

The Carr is the largest of eight big fires burning in California, and 90 across the country, according to the National Interagency Fire Center.

There are currently 12,000 firefighters battling the flames across the state.

Wildfires are a common occurrence in California during the state's long, hot, dry summers.

However, experts say this has been the worst start to the fire season in 10 years - partly due to the 2012-2017 drought that killed off large amounts of vegetation.

UCLA climate scientist Daniel Swain told the Los Angeles Times much of the state's vegetation had reached "explosively dry" levels.

In December, Governor Jerry Brown said devastating wildfires fuelled by climate change had become "the new normal", and that large fires "could happen every year or every few years".