(CNN) -- Fueled by dry timber that hasn't burned in a century, a wildfire in central California grew to more than 16,000 acres and is threatening more than 2,000 homes near Yosemite National Park, a fire official said Sunday.
The fire blazed in areas that haven't burned in 100 years near Yosemite National Park on Saturday.
"This thing is burning in every different direction," said Daniel Berlant of the California Department for Forestry and Fire Prevention. "That's what made it so difficult for us to really get our ... containment lines around it."
Some 200 of the homes in Mariposa County on the outskirts of Yosemite park are "immediately threatened," and under mandatory evacuation orders, he said. Other residents are just being warned that they may have to leave "at a moment's notice" because of the approaching blaze.
"These are very scattered rural areas, but we do have about 2,000 homes that are in the path of the fire so that does have us concerned," Berlant said. "We're working very closely with the local sheriff's department there to help get residents out of the area." Watch wildfire torch hillside »
The fire also caused officials to cut power to the park, The Associated Press reported Sunday.
The fire began Saturday as a result of someone target-shooting in the woodland area, he said. It charred some 1,000 acres near the town of Midpines, but it exploded in size on Saturday.
"It's burned over 16,000 acres now, it's really burning in areas that haven't burned in 100 years," Berlant said Sunday. "So the vegetation is extremely dry and there's a lot of it to burn."
Berlant said 900 firefighters are on the scene with "hundreds more" en route. The fire is burning in steep terrain and firefighters on Saturday used a military plane to drop retardant on the blaze.
"As soon as sun comes up here in California, we're really going to hit it hard from the air," he said.
No structures have been lost to the fire, and no one has been injured, he said. But Berlant said the quickly moving fire is a major concern for California firefighters.
"When you see such erratic fire behavior -- we had reports of over 100-foot flames -- that's a huge challenge for us," he said.
"But we are doing our best right now, and we're making good progress."