SAN DIEGO - The stunning explosion of fires around San Diego County -- eight in all, seven still burning -- stirred suspicions of arson and sent thousands of people fleeing from their homes beginning Tuesday.
Fire crews hoped milder winds, lower temperatures and higher humidity Friday would help them get an edge on the fires, which have burned across more than 17 of San Diego County's 4,206 square miles, according to authorities.
Mike Mohler, a spokesman for the California Department of Forestry and Fire Protection, said he was "cautiously optimistic" the day would see major gains.
Firefighters, aided by civilian and military aircraft, had largely contained a few of the fires, but officials said that the 1,200-acre San Marcos/Cocos fire remained "very active" and that two other fires near Marine Corps Base Camp Pendleton were largely uncontained.
The Las Pulgas fire plaguing the sprawling military base had grown to 8,000 acres and was 5% contained, the base said in a statement on Facebook. Some areas of the base had been ordered to evacuate.
Ash and smoke filled the air in many places, making breathing difficult.
So far, injuries have been few: Authorities found a charred body in Carlsbad, but it was unknown whether the person died because of the fire. A Camp Pendleton firefighter suffered heat exhaustion.
Homes, other buildings destroyed
With the fires still burning, damage estimates are hard to come by. But Carlsbad officials say fire there destroyed at least eight homes, two commercial structures and an apartment building.
The number of people or homes still under evacuation orders was unclear early Friday.
In Escondido, more than 15,000 residents were told to evacuate. The evacuation zone included a 12-story hospital, Palomar Medical Center West, but authorities ultimately told workers there to shelter in place.
Evacuation orders for some 10,000 people in Carlsbad had been lifted, as had similar orders for some of the 5,000 homes evacuated in San Marcos.
Still, thousands of homes across the county are still in jeopardy.
"I've been doing this for 20 years," San Diego County Supervisor Bill Horn told CNN. "This is the worst I've seen."
Images from the fires were jarring.
The night sky glowed orange from towering flames that consumed homes. Whirling columns of flame -- dubbed "firenadoes" or "fire whirls" -- spun across the landscape, in one case nearly devouring a hilltop home.
Firenadoes are spinning columns of flame fed by fuel drawn into the air by naturally occurring vortices created by fire, CNN meteorologist Indra Petersons said. They can spit out winds as powerful as an EF-2 tornado, she said.
CNN's Gary Tuchman saw a wildfire in San Marcos leap hundreds of yards in just seconds.
In video shot by Jeb Durgan and Byron Bowman, a helicopter wheeled over homes, dumping fire retardant just yards from a burning canyon choked with flames. Smoke obscured the road the two were driving on.
"If you imagine standing next to a barbecue or a camp fire and multiply that by a hundred, that's what it felt like for a few seconds," Bowman told "New Day."
The fire, he said, made a "roar like a lion."
Two are investigated for arson
While the causes of the wildfires remain unclear, arson has been a primary suspicion among residents.
Escondido police arrested Thursday night 19-year-old Isaiah Silva and a 17-year-old juvenile, both of Escondido, in connection with arson-related charges stemming from brush fires along Escondido Boulevard and Kit Carson Park, authorities said.
The San Diego district attorney is reviewing the case against the two individuals; no charges had been filed as of Friday morning, said spokesman Steve Walker.
A juvenile court hearing is scheduled for Monday for the 17-year-old youth, Walker said.
Neither Silva nor his attorney could be immediately reached for comment Friday.
Witnesses said two people "appeared to be involved in setting small fires," Escondido Police Lt. Neal Griffin said.
Police don't have reason yet to think the teens were involved in the other fires, but "obviously we will be exploring that possibility," Griffin said.
Remnants of homes
Although many residents have evacuated from their houses, some who have returned came home to just rubble.
"We walked up to this place, and it was like a bomb went off," Anya Bannasch told CNN's "Anderson Cooper 360" on Thursday. "I can't even explain to you how just horrific it was."
Bannasch lost her house, but the entire family -- including the dog -- survived.
"I pray for all the other families, too, out there that are going through this right now, because I know there's fires everywhere."
Evolution of a disaster
The wave of wildfires started Tuesday with the Bernardo Fire in San Diego County. The next day, new blazes popped up -- each one separate from the others, each posing its own dangers.
Scorching temperatures, including record daily highs of 97 degrees in San Diego and 104 in Escondido and El Cajon, certainly didn't help.
Nor did bone-dry conditions:
All of California is experiencing exceptional, extreme or severe drought conditions. The wildfire area is in the second-most dangerous category.
Gov. Jerry Brown cited climate change as a factor in the fires, noting the last three years have been the driest in recorded history.
Fire season in Southern California typically starts late in the summer and extends into fall. But nowadays, "we have year-round fire risk," San Diego County Supervisor Dianne Jacob said.
There's been no time to shut down over the past 12 months, said Chief Thom Porter of the California Department of Forestry and Fire Protection, which is also known as Cal Fire.
"We have never gone out of what you would call fire season," Porter said.
Cal Fire Director Ken Pimlott said that the amount of fire activity statewide so far this year has been "unprecedented."
Here's where some of the major California fires stood as of Friday morning, according to Cal Fire:
The Cocos Fire in San Marcos
• 1,200 acres burned
• 10% of the fire has been contained
• The fire is still very active.
The Tomahawk Fire at Marine Corps Base Camp Pendleton
• 6,300 acres burned
• 15% of the fire has been contained
• A Camp Pendleton firefighter was being treated Thursday for heat exhaustion.
Las Pulgas Fire at Marine Corps Base Camp Pendleton
• 8,000 acres burned
• 5% of the fire has been contained
• Camp Las Pulgas and Camp Margarita were ordered to evacuate.
The Bernardo Fire in San Diego
• 1,548 acres burned
• 90% of the fire has been contained
• Authorities believe the blaze will be fully contained Friday.
The Poinsettia Fire in Carlsbad
• 400 acres burned
• 85% of the fire has been contained
The Miguelito Fire in Santa Barbara County
• 632 acres burned
• 95% of the fire has been contained