Thousands of people remain under evacuation orders after a wind-whipped wildfire raged through rural northern California.

A number of people were injured when the fire that began on Friday afternoon on or near a wood products plant quickly blew into a neighbourhood on the northern edge of Weed, but then carried the flames away from the small city.

Evacuees described heavy smoke and chunks of ash raining down.

Annie Peterson said she was sitting on the porch of her home near Roseburg Forest Products, which manufactures wood veneers, when “all of a sudden we heard a big boom and all that smoke was just rolling over toward us”.

Very quickly her home and about a dozen others were on fire. She said members of her church helped evacuate her and her son, who is immobile. She said the scene of smoke and flames looked like “the world was coming to an end”.

Allison Hendrickson, spokeswoman for Dignity Health North State hospitals, said two people were brought to Mercy Medical Centre Mount Shasta. One was in a stable condition and the other was transferred to UC Davis Medical Centre, which has a burns unit.

Rebecca Taylor, of Roseburg Forest Products, said it is unclear if the fire started near or on company property. A large empty building had burned, she said, but all employees were evacuated and none have reported injuries.

The blaze, dubbed the Mill Fire, was pushed by 35mph winds and quickly engulfed 4sq miles of ground.

The flames raced through tinder-dry grass, brush and timber. About 7,500 people in Weed and several nearby communities were under evacuation orders.

Governor Gavin Newsom declared a state of emergency for Siskiyou County and said a federal grant had been received “to help ensure the availability of vital resources to suppress the fire”.

At about the time the blaze started, power outages were reported that affected some 9,000 customers, and several thousand remained without electricity late into the night, according to an outage website for power company PacifiCorp, which said they were due to the wildfire.

It was the third large wildfire in as many days in California, which has been in the grip of a prolonged drought and is now sweltering under a heatwave that is expected to push temperatures past 37C in many areas through Labour Day.

Thousands were also ordered to flee on Wednesday from a fire in Castaic, north of Los Angeles, and a blaze in eastern San Diego County near the Mexican border left two people severely burned and several homes destroyed. Those fires are now 56% and 65% contained, respectively, and all evacuations have been lifted.