The latest California bush fires left a host of holiday goers running for their lives.

A blaze erupted at a lake near Mammoth Pool campground, forcing 200-plus people to ditch their boats and picnics and seek out safety.

The fire cut off the only road in and out of the area. Local fire officials issued warnings for people to jump in the lake if needed.

Correspondent Richard Arnold told Mike Hosking helicopters came in and were able to rescue many people.

"Some 20 people have been taken off to hospital, six are in the burn unit right now. Needless to say these folks are very, very, very lucky."

Meanwhile a heat record is set to be broken in the Californian desert, which is expected to top 50 degrees Celsius as a heat wave makes its way through the state.