Oct. 1 (UPI) -- A red flag warning went into effect for parts of Northern California on Thursday as deadly wildfires burn throughout the state.
The California Department of Fire and Forestry Protection, or Cal Fire, said the warning indicates that will contribute to fire growth in North and South Bay, central Mendocino County, western Monterey County and most of the Los Padres National Forest and will continue through Friday.
"High temperatures also persist, adding to the critical fire weather danger. A slight cooling trend is not expected until later in the weekend or early next week," Cal Fire said.
The death toll from the fires rose to 30 as a fourth death was reported in the Zogg fire in Shasta County on Wednesday.
Cal Fire said Thursday that the Zogg Fire has now burned 55,303 acres and was 26% contained, while the Glass Fire in multiple North Bay counties had burned 56,781 acres at 5% containment.
Overall 8,100 wildfires -- including five of the six largest in the state's history -- have burned more than 3.9 million acres, destroying more than 7,500 structures in California since the beginning of the year, the agency said.
More than 17,000 firefighters are battling nearly 30 major wildfires currently burning throughout the state.
Fire officials said that "intense fire conditions" combined with wind gusts forced some firefighters to "take refuge ... in the aluminized cloth tents that offer protection by reflecting radiant heat and providing a volume of breathable air."