BEAUMONT -- The progress may be slow going, but it's progress nonetheless.

The stubborn arson-set wildfire near Beaumont was once again powered by strong Santa Ana winds Friday and had ripped across a massive 39,900 acres, or 62 square miles. as of 8 p.m., fire officials said.

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Local firefighters remain on Esperanza fire line

But a day after the blaze started -- a day that was marked with tragedy as four firefighters were killed when overcome by a wall of flames while protecting a home -- there was finally some good news.

Officials estimated Friday night that they now have 25 percent of the Esperanza Fire under control. That containment percentage jumped dramatically from only 5 percent earlier Friday.

A major factor for the progress made, fire officials say, was there chance to finally mount a significant attack.

"We were able to get a lot of resources into the fire area today," Riverside County fire Capt. Rick Griggs said. "That gave us the ability to be more agressive versus being more defensive the first day."

After it first started about 1 a.m. Thursday along Esperanza Avenue in Cabazon, firefighters primarily protected homes and tried to get the best handle on the fire's forward progress as they could.

Hundreds of people were evacuated, flames threatened as many as 500 homes and 10 homes were destroyed Thursday, officials said.

Six firefighters have been injured, including one in critical condition who was also caught in overrun of flames Thursday. Of the other five, one is considered moderate and four minor injuries, officials said.

Moving into canyons

As the fire was pushed by Santa Ana winds to the west Friday, into more desolate and less-populated canyons, firefighters were able to push back a bit more this time, concentrating on knocking it down, not just taking a more defensive stance.

As it did Thursday, smoke continued the hover across much of western Riverside County, raining ash on the region and leading to cancellation of many local high school sporting events.

By Friday evening, there were 2,078 fire personnel assigned to battle the blaze from the ground and the air.

Helicopters dousing flames with water and fixed-wing aircraft -- including a huge DC-10 capable of dropping 12,000-gallon loads of retardant -- dotted the skies above the fire.

All told, there are more than 50 miles of fire line. Now, firefighters must work to keep that line intact and prevent flames from gaining the upper hand.

"This is all a job of connecting the dots while at the same time protecting life and property," Riverside County Fire Chief John Hawkins said.

Tent city housing

The chief spoke from Noble Creek Park in northern Beaumont which has been turned into a fire camp -- a small city of tents and trailers that becomes home for firefighters battling the flames and fire administrators who coordinate the war.

There are now nearly 2,000 firefighters assigned to the battle, coming from all across the state.

Capt. Mario Monroy heads a team of Murrieta firefighters who were at the camp after the crew spent the day setting backfires, which are done to burn off brush so the encroaching fire has no fuel to continue its forward motion.

The four men were preparing to take much-needed showers and say they would be sleeping on cots next to their engine when it came time for them to rest before being sent out to battle once again.

The mood around the camp was somber as firefighters continued to quietly mourn the loss of four of their own who were killed Thursday. A fifth is clinging to life.

The U.S. Forest Service identified the members of its Engine Crew 57 who were overrun by flames as they tried to protect a home.

Forest Service releases identities

Killed were engine Capt. Mark Loutzenhiser, 44, of Idyllwild; engine operator Jess McLean, 27, of Beaumont; assistant engine operator Jason McKay, 27, of Phelan; and firefighter Daniel Hoover-Najera, 20, of San Jacinto.

The injured firefighter was identified as Pablo Cerda, 23, of Fountain Valley, who suffered burns over 90 percent of his body. About 70 percent of the damaged and burned skin was removed by surgeons Friday and Cerda remained in critical condition, said Arrowhead Regional Medical Center spokesman Jorge Valencia.

The reward fund for information leading to the arrest of whoever started the blaze rose to a half-million dollars Friday.

Authorities have said that the arsonist or arsonists could face murder charges for the firefighter deaths.

"We want to catch the killer and the sooner the better and I am hoping that increasing the reward will help," Riverside County Sheriff Bob Doyle said in a news release. "We will not rest until we have captured whoever committed this murder…"

Sheriff's spokesman Sgt. Earl Quinata said the investigation is being headed by the sheriff's Central Homicide Unit and that 40 people are now assigned to the case.

Homicide investigators are working with the FBI, the California Department of Forestry and the Bureau of Alcohol, Tobacco and Firearms.

"Right now we have no real strong leads or anyone identified in this ongoing investigation," Quinata said.

Arson tip line set up

However, since a tip line for the arson case was set up Thursday, authorities have received more than 100 calls, the sergeant said. Investigators are prioritizing those calls to see if any pan out as workable leads, he said.

As teams of investigators are still searching for how started the fire, those assigned to extinguish it still have a massive battle of their own.

Along with the flames themselves, firefighters must also contend with always changing weather conditions as well as the makeup of what is burning.

There were numerous fire crews scattered in the canyons around the fire Friday, as far south as the Soboba Indian Reservation, preparing for any possible change in weather and wind direction.

Crews, many using bulldozers, were shoring up areas to the southeast of the fire, hoping to create areas where it would be difficult, if not impossible, for the fire to continue.

"With Santa Ana winds, all bets are off," Hawkins, the county fire chief said. He said one of the most dangerous times for firefighters is the one-hour lull that happens when those winds reverse.

A forecaster with the National Weather Service said wind warnings will remain in effect until 9 tonight.

"We'll continue to have very low humidity, but the winds should be decreasing by Saturday afternoon," said forecaster Brandt Maxwell -- and begin to change direction as the Santa Ana weather condition breaks down.

"The wind will start coming from the west on Saturday afternoon and by Sunday it will be solidly from the west," Maxwell said. "That will push the smoke (from the fire) out over the desert."

Fire Capt. Griggs said a change in winds could push the blaze more toward the Idyllwild area, but officials are preparing for that possibility.

The fire has mostly been consuming chaparral for fuel as it has raced west and southwest across the region. However as the blaze sweeps out of the hills and into lower levels of Riverside County, it will encounter several non-native grasses, including brome and oats, which are more flammable than the native vegetation it has overgrown, said Richard A. Minnich, professor of earth sciences at UC Riverside.

"These are grasses that have been brought in over the past hundred years," Minnich said. "The area below Beaumont and Banning are dominated by these grasses. That will probably make life more difficult for firefighters at the lower levels."

Idyllwild a different story

If the fire were to shift toward the Idyllwild area it would encounter larger stands of chaparral which, because it had burned in recent decades, is less likely to be good fuel now, he said.

"It's the older stands that are most likely to burn," Minnich said. "The main stand of chaparral in that (Idyllwild) area last burned in 1968 making it only about 40 years old. If the fire gets to Lake Fulmer (about five miles north of the mountain village) and beyond the chaparral there is more than 90 years old and much more flammable."

Minnich said he expects the Esperanza blaze will eventually hit the floor of the San Jacinto Valley, an area dominated by agricultural and dairy land, and run low on fuel.

"I expect that's where (firefighters) will end up making their stand," he said.

Evacuation centers set up

Officials have set up two evacuation centers, including one at Hemet High School. The gym there is serving as a temporary shelter for people displaced by the fire. According to American Red Cross volunteer Rick Hayth, about a dozen people stayed there Thursday night.

Bonnie Stevens of Poppet Flats was evacuated from her house early Thursday and stayed at the shelter overnight.

"They kicked us out of there about 6 o'clock in the morning," Stevens said. "The sheriff came up and said we had to leave. We haven't heard anything except the fire is completely around our little community."

Stevens and her husband originally wanted to go visit family in Yucaipa. But the roads were closed in that direction so they came down Highway 243 to Hemet. Stevens, who sat in the Hemet High parking lot tending to her three dogs, had at least one offer to stay with a family in the area.

Mike Sweeney drove by and offered Stevens a place to stay, where she could keep her dogs. "It made me feel sick," Sweeney said, "what you people have been through. If you don't get a place to stay you are welcome to stay at my place."

Air quality levels in Riverside as a result of the Esperanza Fire were generally deemed unhealthy for people susceptible to breathing problems such as those with heart or lung disease -- except for Perris Valley, Hemet, San Jacinto Valley, Banning and the San Gorgonio Pass areas in which it was deemed unhealthy for everyone, said Sam Atwood of the South Coast Air Quality Management District.

The district recommends that people avoid unnecessary outdoor activities in the smoke-impacted areas and take extra precautions when outside to avoid inhaling a lot of smoke.

Today, the air quality is predicted to improve a little.

Other deadly fires

The Esperanza Fire, while already massive and growing, is still dwarfed in size by one in early September that burned more than 200,000 acres north of Los Angeles and was among the largest in state history.

Wildfires in the fall of 2003 in Southern California killed 24 people, destroyed 3,700 homes, and burned 750,000 acres. The record for firefighter deaths in a wildfire is 14 -- 10 men and four women who died July 2, 1994, on the side of a ravine in Glenwood Springs, Colo., when fire shot up as if sucked through a chimney.

Groups of firefighters have died before, often caught in conflagrations driving by the furious Santa Ana winds that blow this time of year and give each fire tricky, hard-to-foresee patterns. In this case, the winds have been particularly erratic, so much so that firefighting aircraft have not always been able to attack.

Fire service commanders use computer modeling and mapping and other technology and techniques to get a grasp on how a fire is burning and its direction, but a good deal of guesswork and intuition come into play, particularly at the front lines.

"As far as what the fire will do at any particular foot, at any particular second, we can't really say," said Mark Finney, a research forester at the Missoula Fire Sciences Laboratory in Montana. "And those are critical scales for firefighters, and for lots of things: for damage, for effects on vegetation, on houses."

Staff writers John Hunneman, Yvette Urrea, David Carlson, Tom Sheridan and the Associated Press and New York Times News Service contributed to this report. Contact staff writer John Hall at (951) 676-4315, Ext. 2628, or jhall@californian.com.

For those who are looking for relatives or friends who might have gone to one of the evacuation centers, please call the Riverside Chapter of the American Red Cross at 951-656-4218.