As devastating wildfires have destroyed huge swaths of Los Angeles County, incinerating homes and leaving at least 27 people dead, fire and law enforcement authorities have also had to contend with multiple cases of arson.

Firefighters are battling to maintain the upper hand on a huge and rapidly-moving wildfire that swept through rugged mountains north of Los Angeles.

"A Red Flag Warning means that critical fire weather conditions are either occurring now, or will shortly," the NWS said.

San Diego battles wildfires amid 102 mph winds causing evacuations, power outages affecting 50,000 residents and multiple fire outbreaks across the region