A series of red-flag warnings remained in effect until early today, raising concerns about containing two major wildfires in Northern California.

Strong winds, coupled with low humidity, stalled efforts to stop the once-massive Ponderosa Fire in southern Shasta and northern Tehama counties, which remained at 96 percent containment, state fire spokeswoman Julie Hutchinson said.

"We have a line almost completely around it, but it's not a secure line," Hutchinson said.

Elsewhere, authorities in northwest Siskiyou County ordered about 300 residents in Seiad Valley to evacuate as a fast-moving wildfire threatened about 85 homes, but not all residents heeded orders to get out.

"We have a pretty good response, about half of the residents have left," Siskiyou County Assistant Sheriff Jim Betts said.

Fire crews were positioned around the homes and roadblocks were set up to keep people out of the evacuation area.

By Tuesday evening the wildfire had consumed nearly 20 square miles, but no homes had been burned.

Another red-flag warning involved a fire in Plumas National Forest that was 71 percent contained after it scorched more than 114 square miles.

With more than 1,500 firefighters, 140 engines and numerous helicopters battling the blaze, crews were optimistic it could be contained by Friday.

"That's the plan," fire spokesman John Daugherty said. "We want to have a full line around it and hope that it won't jump and take off again."

However, Daugherty said there could be problems, as strong winds approached the southern rim of the steadily burning blaze.

"The fire will continue to burn actively, but we're not expecting any more growth," Daugherty said. "Again, this could be another test."

The warnings could be in effect through Wednesday.

The fires were among eight major blazes actively burning across the state, Hutchinson said.