More than 800 wildfires sparked by an "unprecedented" lightning storm burned a swath of Northern California from Big Sur to wine country to Humboldt County on Monday.

Thousands of firefighters battled the blazes on the ground and from the air and Gov. Arnold Schwarzenegger said he was alarmed by the number of fires that kept erupting.

"You can imagine how shocked I was yesterday when I got my briefings (Sunday) night and I was told that we have 520 fires all over the state of California," he said.

"So it was quite shocking to me, only to find out this morning that that number has actually gone up to 700 and some fires."

Moments later, a top state fire official standing at Schwarzenegger's side offered a grim update: The figure was actually 842 fires, said Del Walters, assistant regional chief of the California Department of Forestry and Fire Protection. All but a couple were in the northern part of the state.

"This is an unprecedented lightning storm in California, that it lasted as long as it did, 5,000 to 6,000 lightning strikes," Walters said. "We are finding fires all the time."

Schwarzenegger said he had enlisted the help of firefighters from Nevada and Oregon, "because you can never prepare for 500 or 700 or 800 fires all at the same time."

Part of the reason for the swelling number of wildfires was that local and state officials were still counting after the fierce thunderstorm Friday night touched off blazes.

"We didn't get real lucky with this lighting storm," Walters said. "It wasn't predicted -- which often happens with these storms that come in off the Pacific, there's no history of the weather as it approaches the shore -- and so we got hammered."

In Mendocino County alone there were 110 fires, with just 17 contained.

Two of the biggest fires had each charred nearly 6 square miles.

One started in Napa County and quickly moved into a mostly rural area of Solano County, and threatened about 250 homes and 50 other buildings as it fed on grassy woodland about 40 miles southwest of Sacramento, said Kevin Colburn, a spokesman for the California Department of Forestry and Fire Protection, or Cal Fire. It was 40 percent contained Monday.

The other was in the Shasta-Trinity National Forest, about 160 miles north of Sacramento, where lightning sparked dozens of blazes. The largest of the fires threatened about 1,200 homes.

Wildfires have destroyed more than 175 homes in Northern California so far this year. Blazes started popping up in the region just as California's unofficial fire season began in mid-May, following the state's driest two-month period on record.

"My hat is off to all the firefighters out there on the ground, dirty, hot, smoky," Walters said. "And it's going to be a long road for us."

Along the coast in the Los Padres National Forest, a 2,000-acre wildfire burning south of Big Sur since Saturday forced the evacuations of 75 homes and businesses, destroyed one house and threatened hundreds of others.

It also led to an emergency airlift Sunday of eight endangered California condors. U.S. Coast Guard helicopters transported the seven juveniles and one adult bird from a wildlife center to the Monterey Airport.

A second fire in the Los Padres burned more than 57,000 acres and has injured nine firefighters.

Two lightning-sparked blazes about 25 miles south of San Jose also forced hundreds of residents to flee over the weekend. The fires covered about 2 square miles. Officials said one fire was 90 percent contained Monday and the other 50 percent contained. Most residents were being let back into their homes.

The third major blaze to hit Santa Cruz County in the past month was fully contained Sunday night after sending more than 2,000 residents fleeing and destroying 10 homes. An earlier 520-acre blaze destroyed 11 buildings in the Santa Cruz Mountains, and a fire near Corralitos covered more than 4,200 acres and destroyed about 100 buildings.

Meanwhile, residents in Brisbane, a small city just south of San Francisco, were being allowed back into their homes after a grass fire scorched several hundred acres on San Bruno Mountain.