A new fast-moving wildfire has erupted in Los Angeles County, prompting tens of thousands to evacuate a region already reeling from the most destructive fires in its history.

The Hughes fire ignited about 45 miles north-west of the city of Los Angeles on Wednesday morning, near Castaic Lake in a mountainous area that borders several residential areas and schools.

The blaze grew to more than 9,200 acres in several hours on Wednesday, fuelled by winds and dry brush.

No homes or businesses have been damaged, and fire officials expressed confidence about getting the blaze under control.