(CNN) -- After four days on the fire lines, they are hot, exhausted, dirty, thirsty and spread way too thin for their own comfort.
Firefighters attempt to take control of the Harris fire in San Diego County early Wednesday.
But the nearly 8,900 firefighters battling 18 blazes in Southern California got a slight break on Wednesday as the humidity rose slightly and the Santa Ana winds shifted and died down a bit.
The relentless westward march of the most devastating Witch and Harris fires in San Diego County halted as the wind began blowing inland from the Pacific Ocean. Some evacuated neighborhoods in San Diego reopened,state fire officials said.
But the change also meant the firefighters had to quickly shift their resources and focus in the battle against three major fires, including a "very precarious" threat to power lines that connect San Diego to the nation's electrical grid.
In Los Angeles County, firefighters gained ground, containing three major fires.
Wildfires from San Diego to San Bernardino to Santa Barbara have burned at least 679 square miles and destroyed nearly 1,600 structures, officials said. Another 2,800 are threatened. Despite the scope of the wildfires, only one fire-related death and 70 injuries, including 34 firefighters, have been reported.
Among the injured firefighters was Linda Lewis' daughter, whose face was burned so severely she was initially thought to be dead.
"Her first response to me was 'I'm sorry,' " Lewis told CNN at University of California-San Diego Medical Center's burn unit. Go inside the famed trauma center »
"She told me that she was in the truck when the fire overtook them and then had to get out of the truck," the worried mother continued. "So that's how with all their protective gear everything was covered, but her face was exposed somewhat; and so that's why she was burned there."
Her doctors said chances are good she will heal, and may even fight fires again.
Every fire agency in California has been called up, said Linda Avery, a spokeswoman with the state Office of Emergency Services in Sacramento. They include 145 state fire engines, 25 local engines, and 26 bulldozers. As the Santa Ana winds die down, additional support is being provided from the air.
Fifteen hundred members of the California National Guard have been called up to provide security and help with evacuations. About 350 of them were in the fire zones of San Diego County on Wednesday, the OES said.
Nevada, New Mexico and Arizona also sent crews to help. According to the OES, Nevada sent five strike teams of 17 firefighters each, 25 engines and 100 firefighters. Arizona sent seven strike teams, 35 engines and 140 firefighters. New Mexico sent three strike teams, 15 engines, 60 firefighters.
Firefighters usually work 12-hour shifts at wildfires, but that can stretch to 24 hours in an emergency. They're on the fire lines for as many as 21 days straight without a day off. Sometimes they eat in chow lines, sometimes they are brought bag lunches. When the flames lead them deep in the back country, they have to settle for MREs.
Some keep in touch with loved ones during short breaks. Firefighter Tom Zeulner, a battalion chief from San Luis Obispo exchanged text messages with his son, Derick, who shared them with CNN with his father's permission.
Early Monday morning, the father said by text message that he was at the Ranch fire in Ventura County. "Love you dad and praying for you and your men," son Derick wrote back.
Tuesday night, son Derick sent a text from San Clemente in Orange County. "You up? No emergency but we have flames just south of San Clemente." Five minutes later, his dad quickly wrote back: "Hi I am in Fillmore tonight lots going on luv dad."
Firefighters throughout Southern California were breathing a collective sigh of relief Wednesday as they heard helicopters and fixed-wing aircraft dropping water and fire retardant in the canyons. The fierce winds were finally dying down enough for the aircraft to fly. Watch firefighters react to the 'sound of joy'
Many of the California firefighters are from urban areas, and are not accustomed to making the difficult choices a fast-moving wildfire demands. Some were fighting their third or fourth fire in as many days.
"The bell went off, they jumped on their engines. They went to Malibu, they went to the Magic fire up there at Magic Mountain, and now we're down here," strike team leader Rick Linsky said from the front lines. "I'm very exhausted. How do you fight the exhaustion? We don't have a chance to rest." Watch the action on the fire lines
"These guys are from Compton, Vernon, Montebello," said strike team leader Linsky. "These are inner-city departments. We're used to going in and busting on a fire for maybe an hour or two, maybe three." Now they've been working for four days.
Linsky reminds his crew of urban firefighters of the alien rules of fighting wildfires. City firefighters try to save everything. Linsky has to teach them when to let a home burn.
"The objective is: Lose a few, save a hundred instead of anchor and save for sure 10 but then maybe lose 80," he said.
Firefighters can't go all-out, all the time, he added. "The winds are going to pick up at night. And at 2 o'clock in the morning, I can't have zombies." E-mail to a friend