(CNN) — The KNP Complex Fire in California has reached a "small area" of the Giant Forest in Sequoia National Park, home to some of the world's largest trees, according to fire officials.
The blaze, which has scorched 21,777 acres, reached the Four Guardsmen area, where officials spent recent days preparing the trees for the threat of fire, per an update Saturday on InciWeb, a national clearinghouse for wildfire information. The base of the General Sherman tree, the world's largest by volume, had been wrapped in an aluminum-based burn-resistant material. But the tree was not impacted by fire on Saturday, the update said.
The KNP Complex Fire was 0% contained as of Saturday. Fire officials expected winds to pick up in the area Sunday, prompting a red flag warning that will remain in effect through the day.
"Crews are preparing for changes and possible significant increases in fire activity," the update Saturday said.
There are more than 600 personnel battling the fire, which was initially made up of three separate fires ignited by lightning earlier this month, according to the National Park Service. One of those was 100% contained, but two -- the Paradise Fire and Colony Fire -- merged Friday and will now be considered a single fire, per InciWeb.
"Our primary focus is on protection of the communities and always will be," Clayton Jordan, superintendent of Sequoia and Kings Canyon National Parks, told CNN Sunday. "And that's where most of the firefighting efforts are focused."
"But we do have a special team of resource managers led by park staff that is focused on the protection of the sequoias while the firefighters deal with the main threat of the fire," he said, adding there are a "number of tools" being used.
One is wrapping trees in the "high-tech, aluminum foil, fiberglass fabric" that was used on the General Sherman tree. The material, Jordan said, works to protect the base of the tree where it may have past fire scars that would leave it vulnerable to fire. It's the same material that firefighters use for emergency shelters, he added.
"It's one of many measures that were taken to try to protect these really important trees," Jordan said.
Last year, between 7,500 and 10,600 mature giant sequoias were destroyed in the Castle Fire -- about 10 to 14% of the world's population of mature sequoias -- according to a report by the National Park Service published in June.
Officials last week were working to mitigate the treat of the fire. But this time the wildfire is burning in places where the National Park Service has no history of fires ever burning, a park official told CNN, meaning there's a lot of overgrowth that could fuel the burn.
"We basically told the fire crews to treat all our special sequoias like they were buildings and wrap them all up, and rake all the litter away and roll away the heavy logs," said Christy Brigham, chief of resource management and science for the Sequoia and Kings Canyon National Parks.