Media caption The fires are being blamed on high temperatures and years of drought, as James Cook reports
The governor of California has declared a state of emergency after wildfires forced about 23,000 people to flee their homes in the north of the state.
Governor Jerry Brown said the fires, which have left one person dead, destroyed and threatened buildings in the Napa and Lake counties.
More than 1,300 people fled Middletown, north of San Francisco, as their homes were consumed by the flames.
Four firefighters who were badly burned are receiving treatment in hospital.
Wildfires were still burning on Monday after devastating homes and apartment blocks over the weekend.

At the scene - James Cook, BBC News, Middletown

You can smell the so-called Valley Fire before you see it. An acrid stench hangs in the air on the road to Middletown. Smoke is thick in the sky, smothering the pines and the dry brush on the hillsides.
But it does not prepare you for the devastation in the little town itself. Home after home lies in ruins. Families who have lost everything have returned to pick through the debris but there doesn't appear to be anything to salvage.
Some houses have survived with scorch marks. Others are unscathed. But everyone here is stunned by the speed and ferocity of the fire which swept through in minutes, whipped up by a harsh, dry wind.
In the heart of this tight-knit community, a twisted mass of metal and ashes was, we are told, an apartment block of nearly 50 homes. The people of Middletown say they will rebuild. That will not be easy.