California wildfires are spreading quickly, threatening hundreds of homes and forcing evacuations at a summer camp where flames temporarily trapped children.

A strong rotten egg smell had Southern Californians plugging their noses and crying foul as air quality experts scrambled to determine if the sulphurous scent was coming from the Salton Sea.

With some of the worst wildfires dying down, many southern Californians lucky enough to find their homes still standing are likely to face hardships for weeks to come.