Firefighters made advances Saturday in their battle against wildfires sweeping Southern California as investigators tried to determine what — or who — started them.
Several of the 11 blazes that had swept through more than 27,000 acres north of San Diego since Tuesday were coming under control as cooler temperatures and calmer winds aided emergency crews working around the clock.
Thousands of evacuated residents were able to return home in some areas, and police ramped up their efforts to find out why so many wildfires began within hours of one another during an uncharacteristic time of year.
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Officials said Saturday that the fire in Carlsbad, one of the worst-affected areas, was fully contained and the Cocos fire in San Marcos, which destroyed eight homes, was 70 percent contained, with full containment expected by Sunday. Evacuation orders were also lifted for this area.
A 57-year-old man has been charged with arson in connection with one of the smaller fires in Oceanside, which started Wednesday. Alberto Serrato pleaded not guilty and bail was set at $250,000.
Witnesses said they saw the man adding dead brush to smoldering bushes in the San Luis River bed, but police do not believe he was the original instigator.
"Unfortunately we don't have the guy that we really want," Oceanside police Lt. Sean Marshand said.
Two other people were arrested in the Escondido area on suspicion of attempted arson. Police said they set off two small fires, which were extinguished within minutes.
Isaiah Silva, 19, was held on $50,000 bail. Details of the second person were withheld because he or she is 17 years old and a juvenile.
There is no evidence their actions were linked to the bigger wildfires but with so many of the fires igniting in a short time Wednesday, officials wonder if some were deliberate.
"Do people have suspicions? Yes," said Carlsbad Police Capt. Neil Gallucci. "But can we confirm them? The answer is no."
Police are speaking to people who have called a tips hotline and will be looking for suspicious footprints or tracks.
"Our investigation might be over quickly for some of these fires — say, if we find a piece of metal nearby from a catalytic converter that back-fired," San Diego County Sheriff Bill Gore said. "But others might not be so easy to determine. We'll be talking to people in the areas to see if they saw anything to see if arson might have had a role."
Only one of the fires in the area has been ruled an accident. The blaze in Rancho Bernardo was caused by sparks from faulty construction equipment, Cal Fire spokeswoman Lynne Tolmachoff said Friday.
The weather has been unseasonably dry, with 50-mph Santa Ana winds and high temperatures in the 90s. In these conditions, fires can be ignited by car sparks, construction equipment, a discarded cigarette or power cables.
The newest fire broke out late Friday near the Marine Corps' Camp Pendleton, already threatened by two wildfires.
The new fire grew to 1,000 acres and was 25 percent contained Saturday. A 15,000-acre blaze that began Thursday was 40 percent contained, and a 6,500-acre fire that started Wednesday at a neighboring Navy weapons station was 75 percent contained.
The charred body of a man was also discovered in a homeless encampment near Carlsbad, local officials said.
In total, the fires are estimated to have caused more than $20 million in damage and forced tens of thousands of residents to evacuate their homes.
Schools, a college campus and the Legoland amusement park were all shuttered, and graduation ceremonies were canceled.
Billowing smoke caused health warnings to be issued across large sections of Southern California.
The worst fire in California's recent history occurred in central San Diego County in 2003, when more than 437 square miles were scorched, nearly 3,000 buildings were destroyed and 15 people were killed.
The Associated Press and The Weather Channel contributed to this report.