LOS ANGELES -- Crews tried to beat back two out-of-control wildfires in Southern California on Tuesday that have kept tens of thousands of people out of their homes even as another round of dangerous fire weather raises the risk for flames erupting across the state.

Fierce winds that drove twin fires through brushy hills near cities in Orange County a day earlier were expected to pick back up, although not to the earlier extremes, according to the National Weather Service.

Southern California Edison reported to regulators that it was investigating whether its equipment might have sparked the Silverado Fire near the city of Irvine. The utility said a wire that lashed a telecommunications line to a supporting cable may have struck a 12,000-volt conducting line above it.

Edison was among the utilities in California that deliberately cut power to customers to prevent equipment from being knocked down or hit with debris in the winds and sparking wildfires. Utility equipment has been blamed for several destructive fires in recent years.

Irvine residents had to evacuate after the fire broke out early Monday, while later and a few miles away, another blaze, the Blue Ridge Fire, sent people fleeing from the Yorba Linda area. One home was reported damaged.

Forecasts call for Santa Ana winds topping 50 mph (80 kph) at times over much of Southern California, with some of the strongest gusts howling through Orange County, where the major fires are.

The winds were so strong Monday that firefighters had to ground their aircraft for much of the day in Irvine, though they got back up by late the afternoon and were expected to fly Tuesday.

Two firefighters, one 26 and the other 31, were critically injured while battling the larger blaze near Irvine, according to the county's Fire Authority, which didn't provide details on how the injuries occurred. They each suffered second- and third-degree burns over large portions of their bodies and were getting help breathing at a hospital, officials said.

Pat McGrath, 78, of Irvine, went to a shelter after someone pounded on her door Monday. The stranger told her about the evacuation orders.

"I just panicked. I started crying," McGrath, who has no family on the West Coast, told the Los Angeles Times. "I'm cold, I'm hungry, I'm stressed, and I don't know what to do."

Southern California Edison cut power to about 38,000 homes and businesses, although it restored some power by Monday night.

In Northern California, easing winds allowed Pacific Gas & Electric to begin restoring power after the largest of five safety shutoffs this year.

At its peak, PG&E cut power to about 345,000 customers -- an estimated 1 million people -- in 34 counties. The nation's largest utility said it had restored power to more than 150,000 customers by Monday evening, with electricity coming back at the other homes and buildings by Tuesday night after crews do inspections to make repairs and ensure equipment is safe.

A dozen reports of damage had been received, PG&E said.

Nearly two dozen wildfires were reported in Northern California on Sunday night and Monday but all were rapidly contained without serious damage.

The threat, however, was far from over in many parts of PG&E's vast service area. A red-flag warning of extreme fire danger was in place Tuesday in the Santa Cruz Mountains near the San Francisco Bay Area and some coastal and valley areas, with warnings extending into Tuesday evening for some higher elevations in the Bay Area.

"Bone-dry" humidity could dry out vegetation, which can contribute to "catastrophic" fires, PG&E meteorology chief Scott Strenfel said.

"The conditions are very, very unsafe," said Mark Quinlan, the utility's incident commander.

However, once the winds ease, the weather should remain calm through the weekend, Quinlan said.

Scientists have said climate change has made California much drier, meaning trees and other plants are more flammable. October and November are traditionally the worst months for fires, but already this year 8,600 wildfires in the state have scorched a record 6,400 square miles (16,600 square kilometres) and destroyed about 9,200 homes, businesses and other buildings. There have been 31 deaths.

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Rodriguez reported from San Francisco. Associated Press writer Amy Taxin in Orange County, California, contributed to this report