SIMI VALLEY, California (CNN) -- Firefighters began Saturday to control a raging wildfire northwest of Los Angeles that has scorched nearly 24,000 acres.
The blaze is 40 percent contained.
So far, the firefighting effort has paid off. Six structures, including homes, have burned but 2,000 others have been saved, fire officials said.
(Watch the wildfire -- 1:36)Los Angeles County Supervisor Zev Zaroslavsky told CNN that residents have also played an important role in preserving their homes by clearing the brush, as required by the county.
"You saw (Thursday) night on CNN homes that were within dozens of feet of the flames and the flames just came to a stop as though there was some supernatural force," Zaroslavsky said. "The reason for it is there was nothing left to burn between the clearance area and the house and the house was saved." (See why California burns -- 2:05)
California Gov. Arnold Schwarzenegger took an aerial tour of the fire Friday.
He praised firefighters at a news conference, saying, "They are doing such a heroic job working day and night to put this fire out, and they have it almost under control."
Schwarzenegger said some of the firefighters and emergency crews had just returned from the Gulf Coast, where they helped in the aftermath of Hurricane Katrina.
Low temperatures, higher humidity and calmer winds helped firefighters establish direct lines around the blaze, which started Wednesday afternoon near Chatsworth and was quickly spread by the dry Santa Ana winds from the northwest.
The cause is under investigation.
Some 3,000 firefighters from Ventura County, Los Angeles County, Los Angeles City, the California Department of Forestry and the National Park Service are battling the "Chatsworth/Topanga" fire, an effort totaling more than $2.8 million.
A few miles to the east, a smaller fire in Burbank continued to spread Friday, burning some 700 acres as 350 firefighters fought the blaze. So far, no homes are in jeopardy as the fire moves up a mountain north of Los Angeles. (Watch the Burbank fire -- 1:49)
Many of the firefighters battling the Chatsworth/Topanga fire were working on constructing a 15-mile fire line to battle the blaze.
The annual Santa Ana winds died down Thursday, but dry conditions continued to fuel the fire. Onshore flow -- moist winds off the Pacific Ocean -- helped firefighters.
Mandatory evacuations were issued hours after the blaze began Wednesday, and the evacuations spread as the Chatsworth/Topanga fire expanded. About 1,500 people were evacuated from the surrounding areas, according to a statement posted on Ventura County's Web site.
Hundreds of evacuated residents have been allowed to return to their homes.
Los Angeles County and Ventura County have each declared a state of local disaster to formalize aid with other agencies and to help recoup the costs of fighting the massive fire.
The fire more than tripled in size from Thursday's 7,000 acres to Friday night's 23,970.
The owner of one destroyed home described his situation as "horrible."
"I'm homeless," David Nenkervis told CNN affiliate KABC after inspecting his property. "God, I can't believe it. Sixty-four years old, and I don't have a home."
CNN's Dan Simon contributed to this report