More than 200,000 homes and businesses remained without power for a second day on Friday after powerful winds toppled trees and power lines and left debris across a wide swath of Southern California.

The fierce gusts that tore across Western states Thursday created a path of destruction that closed schools and prompted some communities to declare emergencies.

The storms, described as a once-in-a-decade event, were the result of a dramatic difference in pressure between a strong, high-pressure system and a cold, low-pressure system, meteorologists said. This funnels strong winds down mountain canyons and slopes.

The system brought high wind warnings and advisories for California, Utah, Nevada, Wyoming, Arizona and New Mexico. The blustery weather was expected to next hit Oklahoma, Missouri and Indiana.

'Off and on'
The violent winds eased but strong gusts still blew through the region Thursday night, at times reaching 60 mph in some California mountains.

Forecasters said the winds would continue Friday, but diminish as the day wore on.

"It looks like we're going to have winds, off and on, through the weekend," said NBC4 forecaster Byron Miranda from Los Angeles.

Read complete coverage from NBC Los Angeles

The winds were also fanning fires in northern California.

The Sacramento Bee reported that more than a dozen fires burned more than 130 acres in El Dorado County. Five fires had also destroyed more than 250 acres in Tuolumne and Calaveras counties.

In Southern California, the storm knocked out electricity to more than 350,000 utility customers. By early Friday, 240,000 of them were still without power.

Gusts, which reached 80 mph, were blamed for toppling semitrailers and causing trees to fall on homes, apartment complexes and cars.

Gene Blevins / Reuters

Local residents look at eucalyptus trees which fell on cars and blocked the street on Avenue 57 after a heavy wind storm in Los Angeles.

A state of emergency was declared in Los Angeles County, where schools in a dozen communities were closed.

In some neighborhoods, concrete light poles cracked in half. Darkened traffic signals and fallen palm tree fronds and branches snarled traffic. At a Shell station, the roof collapsed into a heap of twisted metal.

Heaviest hit area
In heavily damaged Pasadena, schools and libraries closed and a local emergency, the first since 2004, was declared. Officials said 40 people were evacuated from an apartment building after a tree smashed part of the roof.

Pasadena is known for its historic homes and wide oak-lined streets that are frequently depicted in films.

"We still have large trees blocking streets and getting them removed is a priority today," said Lisa Derderian, emergency management coordinator for Pasadena.

About 200 buildings were damaged there. More than 40 buildings were red tagged, meaning they are not inhabitable.

"It will take weeks to get this stuff clear," contractor Tony Martinez told NBC Los Angeles. "We've got some crews, the city has some crews, so if we keep this up we're talking about a month or so."

Many residents Thursday blamed the city for protecting its old trees from over-trimming to such an extent that they have now become a public safety hazard.

Vince Mehrabian, the general manager at A&B Motor Cars, estimated eight Lexus, Cadillac and other luxury cars had been destroyed by fallen limbs. He said he'd been asking the city for four years to trim the trees more.

On a street around the corner, almost every tree was either cracked in half or missing limbs.

Elsewhere, San Diego’s Anna Cearley posted on her Twitter feed how she was kept awake by the wind.

“Thought we were done with #winds in #SanJose but tonight is worse yet. Whistling so loud, can't sleep,” she said on Friday.

Similar stories of downed trees and power lines echoed across the West. Areas hit hard:

Utah
On Interstate 15, strong gusts blew more than 10 semi-trucks onto their sides, prompting authorities to temporarily close the highway to trucks. Commuter train travel was also interrupted after debris covered the tracks.

Schools closed in Centerville, where a 102-mph gust was reported. Mail delivery and trash pickup were canceled.

Davis County issued a disaster declaration to request state assistance, citing more than $3.5 million in estimated damage to infrastructure.

The Red Cross opened three centers to provide food and aid to people affected by the storm, and opened one overnight shelter in Ogden.

Nevada
Weather officials warned that blowing dust was creating visibility problems on a highway between Reno and Las Vegas.

Colorado
In Steamboat Springs, the roof of a four-story condominium complex was blown off and about 100 trees were knocked over, some landing on homes. A ski area shut down its lifts after a gust of 123 mph.

Even some weather experts were surprised by the wind's force.

Jonathan Lloyd from NBC News Los Angeles, msnbc.com's Sevil Omer and The Associated Press contributed to this report.  

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LOS ANGELES - High winds flipped over trees and trucks and knocked out power to more than 300,000 California customers before moving inland early Thursday, where schools in a Utah town closed because of 100 mph wind gusts.

Some of the worst Santa Ana winds in years blasted through California Wednesday and Thursday, sweeping down through canyons and creating gusts of up to 80 mph through the night, with a 97-mph gust recorded Wednesday night at Whitaker Peak in Los Angeles County. High gusts Thursday morning topped 60 mph.

The National Weather Service issued high wind warnings and wind advisories for parts of California, Utah, Nevada, and Arizona, New Mexico and Wyoming.

"What's driving this is a large, cold low-pressure system that's currently centered over Needles, Calif. The strong winds are wrapping around it," weather service forecaster Andrew Rorke said.

The system will sit and spin counter-clockwise over the area for the next day, although "it won't be quite as hellacious" as on Wednesday night, Rorke said.

The pressure front will then begin moving cross-country, eventually bringing blustery weather to Oklahoma, Missouri and Indiana, he said.

An estimated 300,000 customers in Southern California were without electricity Thursday morning and about 26,000 more in the Santa Cruz Mountains of Northern California. San Francisco was spared any blackouts but thousands elsewhere in the Bay area were in the dark.

"We're making a dent in repairs, but we don't know what the winds will bring later this afternoon," Mark Hanson of SoCal Edison said, reported NBCLosAngeles.com.

In Southern California, high winds blew over at least six semitrailers before dawn on highways below the Cajon Pass in San Bernardino County, said California Highway Patrol Officer Mario Lopez. One trucker was taken to a hospital.

Twenty-three flights were diverted and several delayed beginning Wednesday at Los Angeles International airport because of severe crosswinds and debris on runways, officials said. An hour-long power outage Wednesday evening affected all passenger terminals. The winds had died down by Thursday morning but some delays were reported in both arriving and departing flights, Federal Aviation Administration spokesman Ian Gregor said.

Northeast of Los Angeles, foothill communities were hard hit as the winds swept down the San Gabriel Mountains.

Pasadena closed schools and libraries Thursday and declared a local emergency, the first time since 2004. Fire spokeswoman Lisa Derderian said 40 people were evacuated from an apartment building Thursday morning after a tree collapsed, smashing part of the roof.

"We've had several fires, trees into structures, limbs down," Lisa Derderian, Emergency  Management Coordinator for the city of Pasadena, told NBCLosAngeles.com. About 6,000 people lost power in Pasadena, reported NBC.

In nearby Glendale, high winds ripped the roof off a restaurant.

Two house fires, possibly caused by downed power lines, critically burned one person, seriously injured three others and forced seven others to flee, Derderian said. There have been hundreds of reports of wires down, she said. Trees also fell and some roads are impassable.

Overnight, a tree collapsed the canopy of a gas station, but an employee shut off the pumps and no fuel spilled. Another tree toppled onto a car, trapping the driver, who was taken to a hospital.

"We probably have over 100 trees that are down and arcing wires and transformers that have blown," police Lt. Jari Faulkner told the Los Angeles Times.

Across the sprawling suburban San Gabriel Valley east of Los Angeles, hundreds of trees and power lines were down, many blocking streets.

Along Huntington Drive, a major, six-lane thoroughfare that carries traffic into downtown Los Angeles, nearly every traffic light was dark across a distance of more than 10 miles, snarling traffic during the morning commute.

In Arcadia, 15 miles east of Los Angeles, power was out and numerous large trees were blocking residential streets. The local school district closed all of its campuses, including the high school, three middle schools and six elementary schools.

The winds were colder but fiercer than the Santa Ana winds that often hit California in late fall, but they carried the same ability to dry out brush and push fires into conflagrations.

Los Angeles boosted its fire department staffing because of a red flag warning of high fire danger. Early Thursday morning, crews doused a 2-acre grass fire in a park near Occidental College. Downed power lines sparked the blaze in the midst of 80-mph wind gusts.

The National Weather Service’s red flag warning is in effect until Friday evening, according to NBCLosAngeles.com.

Dramatic (and operatic) rescues
In northwestern Los Angeles County, sheriff's deputies rescued two men trapped on a dam spillway near a 200-drop. The men had gone sailing in a 10-foot boat Wednesday but gusting winds kicked up a 5-foot swell and they capsized. They clung to the boat as high winds pushed them to the dam, according to a Sheriff's Department statement.

They were rescued and treated for mild hypothermia, and one man, a former opera singer, was so appreciative that he serenaded the rescuers with "God Bless America," according to the statement.

High winds in Utah overturned several tractor-trailers and knocked out power to more than 30,000 customers. Police asked schools to close in Centerville, Utah, where a 100 mph gust was reported Thursday morning.

In Wyoming, the prevailing winds usually come from the west but the storm is bringing winds from the northeast. The weather service said the shift in the winds could result in more damage than winds of the same magnitude from the normal direction. 

• From NBCLosAngeles: Damaging winds tear through Southern Calif.
• Also on this story: Tree crashes into actress Rebecca Gayheart's home