(NewsNation) — The Washburn Fire on the western flank of the Sierra Nevada, which threatened more than 500 mature sequoias in Yosemite National Park earlier this week was started by humans, local officials are reporting.

“As you all know, there was no lightning on that day so it is a human start,” Yosemite Superintendent Cicely Muldoon said Monday night. “It’s under investigation. That’s all I can say about that right now. We’re looking at that really hard.”

Since the wildfire started in Yosemite National Park about four days ago, firefighters in California have managed to contain the blaze.

Luckily, none of the park’s landmark giant sequoias — the oldest giant sequoia trees in the world that are also the world’s largest tree species by mass — were reported destroyed by the fire, officials said.

“We are starting to see some containment,” Matt Ahearn, operations section chief with California Interagency Incident Management Team 13, said in a video briefing.

The fire has burned 2,044 acres (827 hectares), Ahearn said, without giving a percentage on its containment level.

The park’s Mariposa Grove, home to more than 500 giant sequoias, has been closed since Friday. The community of Wawona — which is located in the park and includes Wawona Hotel and a campground — was evacuated. The rest of the park remains open.

Firefighters set up sprinklers in an attempt to protect giant sequoias, including one named The Grizzly Giant, which is around 3,000 years old.

With their thick bark, giant sequoias have coexisted for millennia with lightning-sparked fires that maintain the health of redwood forests.

Thousands of the trees were destroyed in recent years by fires in California’s Sierra Nevada range, the giant sequoia’s habitat.