Fuelled by hot weather and dense, dry brush, the blaze is threatening 12,000 buildings and key communications masts.
Two firefighters were killed on Sunday after their vehicle was overrun by flames and rolled down a mountainside.
Some 6,600 homes are under mandatory evacuation orders. State Governor Arnold Schwarzenegger described the blazes as "still totally out of control".
The fires also threaten communication towers housing transmitters for all Los Angeles' major TV stations.
Mount Wilson, where the towers are located - near the city of Pasadena - is also home to a historic solar observatory.
Log in to comment