LOS ANGELES, July 11 (Xinhua) -- Authorities said Monday that more than 500 firefighters are battling a fast-moving wildfire to protect some of world's oldest and largest trees in the Yosemite National Park, one of the most visited national parks in the United States.
The Washburn Fire, reported Thursday afternoon, has grown to over 2,340 acres (around 9.47 square km) and is only 25 percent contained, threatening the Mariposa Grove of Giant Sequoias, the largest sequoia grove in the park.
Located in the southern portion of Yosemite, the historic tree grove is home to over 500 mature giant sequoias, including the 3,000-year-old Grizzly Giant tree.
"A full initial attack response was dispatched including Yosemite National Park Fire resources and state and local cooperators," said an incident update released by the InciWeb, an interagency all-risk incident information management system in the United States.
A total of 545 firefighters are working at the scene, an increase of 185 personnel compared to the previous day.
The fire was active Sunday night and with the current warming trend, increased fire activity is expected for Monday as well, officials noted.
While structure wrap is not currently being used on the giant sequoias, firefighters are proactively protecting the Mariposa Grove through the use of a ground-based sprinkler system. This increases the humidity in the area around the trees and combined with the removal of ground fuels, the ground fire risk is greatly reduced, according to the update, adding that Yosemite's fire management program has for many years utilized a wide variety of methods to reduce the fuels and minimize the risk of fire to the over 500 mature giant sequoias as well as the entire national park.