REDDING  (AP) — Firefighters said Monday they hoped to contain two major wildfires this week after the blazes ravaged huge swaths of Northern California.

The Ponderosa Fire was 85 percent contained after consuming more than 43 square miles and destroying more than 140 structures, officials said.

Hundreds of evacuees were allowed to return home and road closures were lifted, but a red flag warning was issued Sunday as strong winds tested the containment lines firefighters had built over the past several days.

Another warning is likely on Tuesday for the fire located about 25 miles east of Redding and about 150 miles north of Sacramento, CalFire spokeswoman Julie Hutchinson said.

"The winds are still presenting a lot of challenges," Hutchinson said. "Right now, the most significant thing is that we don't have any new and emerging large fires, but we do have some with no perimeter lines, and that could cause fires to grow very rapidly because of the winds."

Meanwhile, a second major blaze burning in the region, the Chips Fire in Plumas National Forest, was 68 percent contained after scorching more than 104 square miles. However, the fire remained stubborn and continued to burn, especially along its southern rim, fire spokesman Larry Helmerick said.

"That area is still giving us problems," Helmerick said. "It's just situated in a rugged terrain in some nasty country, some places so bad we can't put boots to the ground."

Helmerick said more than 1,500 firefighters, 140 engines and nine helicopters — including four air tankers— were trying to help reinforce containment lines and put out spot fires at the scene.

One tanker made 14 water drops alone on Saturday, he added.

Crews expected the blaze that began on July 29 to be contained by Friday, Helmerick added.

A third fire burning outside the Mendocino County community of Covelo was 34 percent contained after consuming 42 square miles.

Also, in northwest Siskiyou County, the sheriff's office issued a pre-evacuation notice to residents in Seiad Valley after a series of fast-moving wildfires burned more than 20 square miles.

Sheriff's deputies and search and rescue teams planned to go door-to-door notifying residents that a potential threat of fire is about 12 hours away.

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Associated Press Writer John S. Marshall in San Francisco also contributed to this