Update: A campfire set by people "partying" in the woods may have started a huge wildfire that destroyed dozens of homes near Malibu, California, on Saturday.
Two fire investigators told CNN on Sunday the blaze may have originated at a campfire set at the end of a dirt road, where investigators have determined the 4,720-acre Corral Canyon fire began.
The investigators, speaking on condition of anonymity because the investigation is ongoing, said they hope the people will come forward.
The Los Angeles County Fire Department said the Corral Canyon fire was 40 percent contained as of Sunday afternoon. The Malibu city Web site said officials expect to have the fire fully contained by Tuesday.
"Given the weather conditions, the wind subsiding ... the amount of fuel that has been consumed in there ... the number of personnel that we have here ... those are all reasons for optimism," Los Angeles County Fire Chief Michael Freeman told reporters Saturday night.
The wildfire began early Saturday and, fueled by dry Santa Ana winds and low humidity, grew quickly, forcing thousands to evacuate. Fire-friendly weather conditions hindered initial efforts to battle the blaze, which consumed dozens of homes in Los Angeles County.
Los Angeles County Fire inspector Sam Padilla said more homes were threatened, and the number of burned structures -- which stood Saturday at about 50 -- was expected to increase.
Of the 1,700 firefighters battling the fire, a handful received minor injuries, fire officials said. One suffered moderate facial burns, department spokesmen said.
Sia Hodjatie, who lives near Corral Canyon, told CNN Saturday that his older son had called to inform him he may have lost his home.
"I woke up around 3:45 [6:45 a.m. ET] and I smelled the smoke, and I woke up my wife. I said, 'Ursula, get up, there is a fire.' She says, 'I don't see it.' I said, 'But I smell it.' "
Hodjatie said he and his family fled their house about an hour later. "My older son was saying, he said, 'Dad, if we had left 30 or 40 seconds later, we would have been baked here.'"
Red Hot Chili Peppers bassist Flea, whose real name is Michael Balzary, told the Los Angeles Times by text message that his home had "burned to a crisp."
Gov. Arnold Schwarzenegger reactivated a state of emergency he declared for last month's devastating California wildfires, pledging he would make quickly available resources to affected Californians.
"No time is wasted in providing any needed resources to fight these fires or help those Californians who have been impacted," he said in a statement.
Operations centers run by the Office of Emergency Services in Los Alamitos and Sacramento were prepared to meet requests for assistance from Los Angeles County, the governor said.
Mandatory evacuations remained in effect Sunday for the area bordered by Corral Canyon to the east, Kanan to the west, Mulholland to the north and Pacific Coast Highway to the south. The Red Cross set up evacuation shelters at Agoura High School and Channel Islands High School, Red Cross spokesman Nick Samaniego said.
Despite thousands of evacuees, only a handful of people arrived by mid-day Saturday at Agoura, he said. "It's a good sign, it shows that people have other resources," he said.
Many residents and officials Saturday were plagued by an unpleasant sense of deja vu.
"I could hear the wind, then I heard the noise of a helicopter, and I thought, 'That can't be good,' " Malibu Mayor Jeff Jennings said Saturday.
Last month's fires charred more than 508,000 acres in several counties, and forced 1 million people from their homes.
However, Jennings remained optimistic. It's "certainly not as bad as it could have been," Jennings said. He urged residents to "listen to the radio; stay alert; stay vigilant."
CNN's Ted Rowlands contributed to this report.
Previously: A "dangerous and dynamic" wildfire in Southern California that left six firefighters hurt and destroyed dozens of homes grew to 4,650 acres Saturday night, officials said.
But firefighters have been able to contain 25 percent of the blaze, according to the Los Angeles County Fire Department.
They got a slight break when dry Santa Ana winds clocked at 57 mph (92 kph) earlier in the day decreased to about 20 mph, CNN meteorologist Jacqui Jeras said.
But the winds, blowing from the west, were unpredictable.
"Until the fire is knocked down, we can't be sure what the next development will be," Los Angeles County Supervisor Zev Yaroslavsky said at a news conference earlier.
About 10,000 people fled their homes in the Malibu area ahead of the flames, which began around 3:30 a.m. PT (6:30 a.m. ET).
The fire has also knocked down power lines, said Los Angeles County Fire Chief Michael Freeman. About 1,700 firefighters were battling the blaze, aided by 23 aircraft.
Gov. Arnold Schwarzenegger pledged to make available help that was offered during the devastating fires in the region a few weeks ago.
"The state of emergency I declared last month has been reactivated, so no time is wasted in providing any needed resources to fight these fires or help those Californians who have been impacted," he said in a statement.
An enormous number of resources were being devoted to the fight, said Malibu Mayor Jeff Jennings.
"I'm standing on my deck of my house here, and I can see four helicopters ... all attacking the fire at once. So they are going after it in a hurry, there's no doubt about that," he said.
It's "certainly not as bad as it could have been," said Jennings, who urged residents to "listen to the radio, stay alert, stay vigilant."
The fire destroyed 51 homes and damaged 27 by Saturday evening. The flames also damaged a mobile home and eight vehicles.
"Whenever these fires are pushed by ... winds, it's a like a blow torch with a hair dryer behind it," said Inspector Sam Padilla of the Los Angeles County Fire Department.
The fire started on a dirt road next to a paved highway in the Corral Canyon area, Freeman said.
Officials said that it's unclear how the wildfire started, and that arson investigators were on the scene.
Mandatory evacuations were ordered in the area bordered by Corral Canyon on the east, Trancas Canyon on the west, Mulholland to the north and the Pacific Coast Highway on the south, although some were lifted later Saturday.
The Red Cross set up a shelter at Agoura Hills High School. Evacuated residents farther south were instructed to go to Channel Islands High School in Ventura County.
A resident who was not told to evacuate did so anyway, and he told CNN he thought his home had been destroyed.
Sia Hodjatie said the smell of smoke awoke him about 3:45 a.m. He and his family packed their pets into their car and started leaving the house an hour later.
"When we were leaving, the fire was in our back door," Hodjatie said. "My older son ... said, 'Dad, if we would have left 30 or 40 seconds more, we would have been baked here.' And we saw the fire coming toward the house, and heavy smoke, and very, very uncomfortable situation."
Thick smoke billowed into the air and could be seen several miles from the flames, witnesses said. The fire is producing a "tremendous" amount of smoke, Pepperdine University official Jerry Derloshon told CNN.
Looking westward, where the fire was several miles away, he said, "There's so much smoke, it almost defies understanding."
Pepperdine students were being asked to relocate to a central location on campus as a precaution, he said.
Maurice Luque, a spokesman for the San Diego Fire Department, said their firefighters were ready in case the fire spreads there. The city is about 130 miles southeast of Malibu.
"We're very, very concerned. We're on high alert. Our fire crews have been told to be ready to come in off duty. They all have their equipment with them, so they can report anywhere they're needed."
"We're hoping and praying that the winds do not materialize down here, that we have no fires, and there's no need for additional resources down here if something breaks. It's a very tense, nervous situation," Luque said.
It was the second time in just over a month that fires ravaged the region. Last month's fires charred more than 508,000 acres in several counties, destroying about 1,600 homes, causing 14 deaths and forcing 1 million people from their homes.