A wildfire in Yosemite National Park that has spread over 1,500 acres is threatening a grove of hundreds of giant sequoia trees, including some that are centuries old.

The fire, now entering its fourth day and fueled by timber and brush, is active in the Mariposa Grove, the largest and most popular of the park’s three giant sequoia clusters. The grove is home to some of the longest-living and tallest trees in the world, including a tree named the Grizzly Giant that is more than 200 feet tall.

Nancy Phillipe, a Yosemite fire information spokesperson, said the fire was 0% contained and that there was not yet any estimate of damage to the sequoia trees.