POLLOCK PINES, Calif. >> Assessment teams hope to get an idea Saturday of just how many structures have been damaged or destroyed by a massive wildfire that threatens thousands of homes in Northern California.

While officials confirmed that several structures have been lost in what is being called the King Fire, dangerous conditions have prevented them from determining an exact number, fire spokesman Mike McMillian said. The blaze began one week ago, and a man accused of starting the blaze is being held on $10 million bail.

Although record amounts of retardant have been dropped on the fire that’s about 60 miles from Sacramento, the blaze spread another 6 square miles overnight as forecasters say smoke from it could be seen in the San Francisco Bay Area. Nearly 5,000 firefighters — from as far as Florida and Alaska — are helping California crews battle the blaze that’s not only consumed grass and brush, but swaths of extremely dry tall timber.

"That’s what makes it difficult for a direct attack," McMillian said. "The main fuel that is burning is the tall timber. We’re making some progress, but it is slow going in some areas as we’re trying to construct more contingency and control lines."

Also of concern is possible wind gusts of up to 30 miles-per-hour that could push the fire, which has spread north to the south, state fire spokeswoman Lynne Tolmachoff said.

"That would open up a whole new area for it to burn in," Tolmachoff said.

The fire has spread to the Tahoe National Forest northwest of Lake Tahoe, McMillian said. Also, the fire is threatening a key University of California, Berkeley research station that his home to scores of experiments on trees, plants and other wildlife.

Burning in rugged, steep terrain, the wildfire has consumed about 126 square miles and forced the evacuation of 2,800 people and burned multiple structures in the White Meadows area of Pollock Pines. More than 21,000 structures are threatened as the fire is 10 percent contained.

Wayne Allen Huntsman, 37, pleaded not guilty to an arson charge Friday in El Dorado County Superior Court.

Authorities have not said what evidence they have linking Huntsman to the fire, by far one of the largest of about a dozen fires burning statewide.

Meanwhile, a fire in Weed and another near Oakhurst that destroyed or damaged more than 200 structures combined are close to full containment, officials said Saturday.