Some 12,000 firefighters are battling 560 active wildfires across California, state Governor Gavin Newsom said.
Major fires in Southern California are coming under control, and the state is shifting resources to battle massive blazes in Northern California, USA TOday quoted Newsom as saying on Friday.
There, fires have burnt through brushland, rural areas, canyon country and dense forest surrounding San Francisco.
"We're putting everything we have on this," Newsom said, noting the state is seeking aid from the federal government.
California firefighters are "overwhelmed" by the ongoing fires, he said.
Two of the fires there are now the 7th and 10th largest fires in state history, having burned as much as 300 square miles each, Newsom added.
Meanwhile, the CZU Complex fire raging through San Mateo and Santa Cruz counties is 50,000 acres and has displaced about 64,600 people, Xinhua news agency quoted the California Department of Forestry and Fire Protection (CAL Fire) officials as saying on Friday.
With one big fire burning a mile north of the University of California, Santa Cruz, the school has evacuated about 1,200 people as its Chancellor Cynthia Larive issued an emergency declaration, ordering all students living on campus and employees to leave.
Four people have been killed from LNU Lightning Complex fire which is some 219,000 acres with 7 per cent containment as of Friday.
Three people were found dead at a burned home in Napa County on Wednesday, a spokesman for the Napa County Sheriff's Office confirmed Thursday night after officials recovered their remains.
The fourth victim of the LNU Lightning Complex died in Solano County, according to a report of the San Francisco Chronicle.
Smoke from the fires is making the air quality in parts of California some of the worst in the world.
Health experts say limiting outdoor activities, remaining indoors with the windows and doors closed and turning on an air conditioner with a recirculation setting can help reduce your risk if you live in an affected area.