SACRAMENTO, Calif. -- Gov. Arnold Schwarzenegger on Friday doubled the number of National Guard soldiers helping battle fires that have scorched hundreds of square miles in Northern California.

Two hundred soldiers are expected to go to the Wildland Fire Training Center at McClellan Air Park early next week to train, according to a statement from the California National Guard.

Schwarzenegger already sent 200 other soldiers to duty as ground firefighters earlier this week.

More than 20,000 state firefighters are on the lines, with shifts extended to 21 days without a break.

One fire chief said he's never seen resources stretched so thin so early in the fire season.

"It's dire. We are in perilous times. This is an extreme emergency," Cal Fire's Mike Richwine said.

National Guard aviators have been flying fire suppression missions since widespread fires broke out in the region.

A total of 367 wildfires were burning around the state, most ignited by lightning, according to the California Department of Forestry and Fire Protection and the U.S. Forest Service.

That figure was down from a peak of roughly 1,500 fires just a few days ago.

In all, the wildfires have scorched more than 790 square miles and destroyed at least 65 structures around California since June 20, according to the Cal Fire.

Near Big Sur, at least 20 homes have been destroyed since the blaze broke out June 21. The fire was only 5 percent contained.

On Thursday, officials also reported California's first firefighter death this year -- a volunteer who collapsed on the fire line in Mendocino County.

Meanwhile, fire activity in Butte County led to the closure of Highway 70 from 3 miles west of Pulga to the junction of Highway 89.