The firestorm that's engulfed parts of Southern California has fire crews keeping an eye on "unprecedented" wind gusts as they work to fight the flames on what officials have described as "steep, inaccessible areas."
The National Weather Service has extended a red-flag warning through the weekend across much of the region, which indicates "critical" fire conditions exist in Los Angeles and Ventura Counties, where fires have destroyed hundreds of homes since Sunday.
"If fire ignition occurs, there will be the potential for very rapid spread of wildfire with long-range spotting and extreme fire behavior that could lead to a threat to life and property," the weather service warned.
Fire officials warned those powerful winds can help to fan dangerous flames in any blaze that develops.
"These winds are pretty much unprecedented," Los Angeles County Fire Battalion Chief Trent Aronson told Fox News on Thursday.
Aronson said the blazes this week have been particularly challenging because 60-mile-per hour wind gusts don't allow firefighters to actually fight the flames, but instead are simply taking precautionary measures to slow the spread.
At least five fires are currently tearing through Southern California, after a new blaze erupted Thursday in San Diego County. State fire officials said the Lilac Fire was "growing at a dangerous rate of spread," and so far has burned 2,500 acres and destroyed at least five buildings, according to Cal Fire.
California Gov. Jerry Brown declared a state of emergency late Thursday for the area, known for its equestrian facilities.
Crews battling the Skirball Fire that's burned 475 acres in LA are facing two extremes – very warm and windy conditions during the day and cold conditions at night, according to Aronson.
"These winds are pretty much unprecedented."
In the initial days of a firefight, fire crews can work for a couple of days straight before reinforcements arrive, Cal Fire Spokeswoman Lynnette Round told Fox News.
Each incident team on the fire lines have a medical unit with them, but physical exhaustion also begins to set in for crews as the wildfire fight stretches into days, Aronson added.