(CNN)One person has died as a result of a growing wildfire in Northern California, officials said Friday.
Officials didn't identify the person who died and were still trying to notify the person's relatives. Authorities have not yet determined how the person died.
Siskiyou County Sheriff Jon Lopey said the individual was found in a structure in Hornbrook.
The Klamathon Fire has burned 9,600 acres in the state and, as of Friday evening, parts of southern Oregon.
It was spreading to the east and officials were calling for more people to evacuate. So far about 400 people have been told to leave their homes.
The fire, which started Thursday, prompted authorities to briefly shut down Interstate 5 in both directions.
Firefighters have been working in tough conditions with the area under a red-flag warning for strong winds and high temperatures for more than 48 hours. Conditions will ease Saturday, said fire analyst Tim Chavez of Cal Fire.
The fire is 5% contained and has destroyed 40 structures, officials said. The blaze is one of about 10 major fires burning in the state, the largest of which is known as the County Fire.
It has burned more than 88,000 acres in Napa and Yolo counties and is 42% contained.
To the south, a 400-acre brush fire in east San Diego County is chewing up homes in the densely populated suburb of Alpine.
Cal Fire authorities do not have an exact number of destroyed homes immediately available, but aerial footage shows at least a dozen.
One firefighter suffered burns while working on structure protection at a mobile home park near where the fire began, according to Olivia Walker, a spokeswoman for Cleveland National Forest.
Bill Paskle, chief of the Alpine Fire Protection District, said the injured firefighter is expected to be released from the hospital Saturday morning. The firefighter, who has minor burns on his face, is in very good spirits, the chief said.
Hundreds of people living and working in the vicinity have been evacuated.
The cause of the fire is under investigation, Cal Fire Capt. Kendal Bortisser said.