Officials in Southern California now believe it could take up to a fortnight to bring wildfires under control.
The Los Angeles County Fire Department says only 5% of the fires have so far been contained.
The fire has been burning since Wednesday. It is being fuelled by extremely dry brush that has not burned in more than 40 years.
More than 48,000 hectares have burned and about 6300 houses are under evacuation orders. Two fire fighters died on Sunday.
The BBC reports the blaze broke out in the Angeles National Forest and has spread to Los Angeles's northern suburbs, 25km from the centre. The fire is only 5% contained.
Governor Arnold Schwarzenegger has declared a state of emergency and urged people to comply with evacuation orders.
A number of other fires are also burning in southern and central California.
