Three people have died in a wind-whipped Northern California wildfire that has forced thousands of people from homes while carving a 40km path of destruction through mountainous terrain and parched foothills.
One person was found in a car apparently having tried to escape the flames, while hundreds, if not thousands, of homes are believed to have been damaged or destroyed by the blaze northeast of San Francisco.
The fire has also threatened Paradise, a town devastated two years ago by the worst blaze in the state's history that prompted a deadly traffic jam as panicked residents tried to escape.
The North Complex fire was one of more than two dozen burning in California including three of the five largest ever in the state.
Other wildfires charred huge swaths of the west amid gusty, dry conditions. Forecasters said some relief was in sight and could help firefighters overwhelmed by the blazes.
In Washington, more hectares burned in a single day than firefighters usually see all year, while unprecedented fires have all but destroyed five small northwestern towns in Oregon with multiple deaths feared.
Fires also forced people to flee homes in Idaho but a blast of polar air thankfully helped slow fires in Colorado and Montana.
Since the middle of August, fires in California have killed 11 people, destroyed more than 3600 structures, burned old growth redwoods, charred chaparral and forced evacuations in communities near the coast, in wine country and along the Sierra Nevada.
Thick smoke on Wednesday choked much of the state and cast an eerie orange hue across the sky as thousands of people in communities near Oroville were ordered to evacuate.
Daniel Swain, a climate scientist at the University of California, conservatively estimated the fire had burned about 1036 square kilometers in 24 hours.
"The unbelievable rates of spread now being observed on these fires - it is historically unprecedented," he tweeted.
The US Forest Service, which had taken the unprecedented measure of closing eight national forests in Southern California earlier in the week, ordered all 18 of its forests in the state closed Wednesday.
The fire raging outside Oroville, northeast of San Francisco, jumped the middle fork of the Feather River on Tuesday and, driven by 70 km/h winds, leapt into a canopy of pines and burned all the way to Lake Oroville - 40km away.
Mill City, an Oregon town with about 1900 residents west of Detroit, had major damage on its outskirts and homes destroyed along the Santiam River.
To the south, parts of Medford, Oregon, a popular retirement location with over 80,000 residents in the scenic Rogue Valley, were under evacuation orders as a growing wildfire closed a section of Interstate 5.
The fire moved north to Medford from Ashland, where it started on Tuesday, heavily damaging the small towns of Talent with about 6000 residents and Phoenix, with around 5000.