(USA TODAY) -- Two teens were arrested Thursday evening after police say they started at least two brush fires in San Diego's Escondido area, as a number of larger fires rage across the county.
Police arrested 19-year-old Isaiah Silva of Escondido and a 17-year-old juvenile on suspicion of attempted arson after a witness unsuccessfully tried to chase the teens, who were on bicycles, NBC San Diego reports.
Lt. Neal Griffin of Escondido police said investigators could not yet connect them to any of the larger fires currently burning across the county that have have driven tens of thousands from their homes and shut down schools and amusement parks.
A red flag warning, which means that critical fire weather conditions are either occurring now or will shortly, are in effect in Hanford, Oxnard and San Diego, according to the National Weather Service.
Flames have charred more than 15 square miles and caused more than $20 million in damage, burning at least eight houses, an 18-unit apartment complex and two businesses.
Firefighters found a badly burned body Thursday in a transient camp in Carlsbad — the first apparent fatality — and a Camp Pendleton Fire Department firefighter was treated for heat exhaustion while battling a square-mile blaze on the Marine base.
The fires are fed by brush and trees left brittle by prolonged drought. They are also being whipped by a Santa Ana wind system that reverses the normal flow of wind from the Pacific Ocean and creates tinderbox fire conditions.
As of Thursday, for the first time this century, the entire state of California is in a severe drought -- or worse. The three worst levels of drought are severe, extreme and exceptional: 100% of the state is now in one of those three categories: (23.31% severe, 51.92.% extreme and 24.77% exceptional.)
A flare-up Thursday prompted 18,400 new evacuation notices in and around San Marcos, a north San Diego, suburb. But with cooler temperatures forecast, there was an overwhelming sense that far more damage could have been inflicted on a region of more than 3 million people.
It could take months to find the causes of the blazes concentrated in the northern San Diego and its northern suburbs, from the coast to areas 10 to 15 miles inland.
San Diego County Sheriff Bill Gore said arson will be among the many possibilities that investigators will look at in trying to determine what caused nine fires to break out during a heat wave, including eight in one day. The first fire started Tuesday.
Contributing: Doyle Rice in McLean, Va.; Associated Press