Yosemite National Park’s largest and most iconic sequoia grove remained threatened by a wildfire Sunday afternoon as rough terrain and hot weather proved difficult for battling the blaze.

The Washburn Fire was first reported Thursday in Yosemite’s Mariposa Grove, which houses over 500 mature sequoias, including the 3,000-year-old Grizzly Giant. It quickly spread amid hot and dry weather conditions: the fire grew to 2,000 acres Sunday evening, up from 466 acres recorded on Friday, according to the National Wildfire Coordinating Group.

The Washburn Fire also threatened the small nearby community of Wawona, forcing people to evacuate their homes and campsites Friday night. 

As of Sunday, afternoon the fire remains 0% contained, the National Park Service said.  The National Weather Service in Hanford, California, forecast moderate to heavy smoke impacting Yosemite on Sunday.

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The terrain and climate have presented a challenge for firefighters: on top of hotter and drier weather conditions Sunday, they have to navigate through dead, fallen trees and other dead foliage caused by large numbers of tree deaths from 2013 to 2015 — a “significant safety hazard,” the National Wildfire Coordinating Group said. 

The hot and dry conditions are expected to extend throughout the week, the National Parks Service said, although winds will be light. The parks service anticipated that fire activity will continue to actively spread during the next three days and beyond. 

Firefighters are throwing “every tactic imaginable” at it, said Nancy Phillipe, a Yosemite fire information spokesperson. That included air drops of fire retardant as well as the planned use of bulldozers to create fire lines, a tactic that’s rarely used in a wilderness setting like Yosemite, Phillipe said.