(CNN) In an attempt to avoid sparking a wildfire, California's largest utility intentionally cut power to hundreds of thousands of customers Wednesday, and power isn't likely to be restored for days, the company said.

Cars lined up to get gas at a station in Vallejo Wednesday.

PG&E shut down power for about 500,000 customers in Northern California early Wednesday, but was able to restore it for about 44,000 during the day, the company said at a press conference. An additional 250,000 customers may lose power later Wednesday, the utility said.

"We took this step to ensure safety as a last resort, and we are committed to reducing the risk of catastrophic wildfire events" Sumeet Singh, vice president of PG&E's Community Wildfire Safety Program, said Wednesday.

Diablo winds sweeping across arid Northern California "historically are the events that cause the most destructive wildfires in California history," said PG&E meteorologist Scott Strenfel.

The wind is expected to subside Friday, Strenfel said. PG&E crews will then examine their system for damage and begin to restore power for customers. That could take several days after the wind dies down, Singh said.

A Starbucks in Sausalito, north of San Francisco, was among the businesses closed Wednesday during a massive, intentional power outage in Northern California.

"We very much understand the inconvenience and difficulties such a power outage would cause and we do not take or make this decision lightly," he said. "This decision ... was really focused on ensuring that we're continuing to maintain the safety of our customers and our communities."

The utility said it expects to restore service to as many as 80,000 more customers Wednesday evening if it can be done safely.

Firefighters were working to put out a grass fire at a wind turbine farm in Solano County Wednesday. Customers in that county were affected by the shutdown.

'Their answer to everything is to just shut it off'

PG&E has come under criticism in recent years for the role of its equipment in a series of catastrophic wildfires across the state, including the deadly 2018 Camp Fire. The utility has agreed to pay billions of dollars in damages.

The company warned in February it could proactively cut power more often and to more customers during risky weather conditions as a means of preventing wildfires caused by high winds downing live power equipment.

The plan, critics say, lets PG&E get away with inconveniencing its customers and costing businesses instead of upgrading its infrastructure to prevent fires.

"I'm angry at PG&E," Blair Roman, a PG&E customer who's out of power in Mill Valley. "Most of my friends are angry as well."

"They didn't do what they were supposed to do and keep up with the lines and the power," Roman said. "Their answer to everything is to just shut it off so we can't get blamed for it. It's a major inconvenience, it's going to cost companies billions of dollars. And it all could have been avoided."

State Sen. Jim Nielsen, whose district includes Paradise, where 85 died in last year's Camp Fire, said the "massive power shutoff is unacceptable."

"This has to change," Nielsen said in a release. "PG&E's decision to protect itself from liability at the expense of hardworking Californians will not be tolerated. This disregards people's livelihoods. We depend on electricity to live and earn a living."

San Jose officials also said they would prefer that PG&E improve its equipment instead of imposing outages.

"We really want to put pressure on PG&E to make investments on their infrastructure to make it safe and reliable so they won't have to shut down when there are weather events," said deputy city manager Kip Harkness. "And we're talking to them and making that stance known to them," he said.

People who live miles away from the risky areas are also impacted

Not all of the customers -- about 2.5 million people, by Nielsen's estimate -- live in an area where there's a higher risk of fires at the moment.

PG&E's new shutoff plan includes, for the first time, shutting down high-voltage transmission lines -- arteries that feed smaller transmission and distribution lines. While this can cut power in risky areas, it also affects others on the grid, even cities where fire risks are not extreme.

"(That's) because of the interconnected nature of our electrical grid and the power lines working together to provide electricity to cities, counties and regions," Singh said.

An empty lantern section at a hardware store in Los Gatos.

State regulators approved this plan, along with rules meant to prepare and warn the public, in May

Some residents facing life without electricity are checking into hotels outside the outage area, CNN affiliate KGO reported

"Most people don't realize what an outage really means," one of those hotel guests, Marilyn Varnado of eastern Oakland, told KGO. "Stop lights are not going to be working. There's going to be a lot of crazy things going on, and I just think there's going to be some tragedies because of that."

By Wednesday, there were long lines for gas and empty store shelves already in some parts.

Several school districts and a major university have canceled classes. And officials in cities such as San Jose are urging people reliant on medical devices to get them charged at certain community centers that will remain powered.

Preparing to be without power for as long as 7 days

San Jose Mayor Sam Liccardo urged residents on Monday to prepare to be without power for as long as seven days.

In San Jose, officials are warning of consequences both inconvenient and potentially life-threatening.

Southern and eastern parts of San Jose are expected to see their power cut. Although PG&E says only 38,000 San Jose accounts will be affected, that could translate to as many as 200,000 of the city's 1 million residents, Harkness said.

Because some traffic lights will be out, people should consider driving as little as possible, Harkness said during a Wednesday news conference.

Police, fire, water, sewer and garbage-pickup services will continue, Harkness said. But he urged people to check on vulnerable people, like the sick, elderly and those who rely on medical devices.

"Prepare yourself, prepare your family, and help your neighbors," he said.

Second phase delayed but many more may lose power

250,000 customers in Alameda and Santa Clara counties and elsewhere, PG&E A second shutoff phase that was expected to start around noon PT Wednesday has been delayed. That will cut power to about250,000 customers in Alameda and Santa Clara counties and elsewhere, PG&E said

A map from PG&E shows the areas where power may be cut.

A third stage has been significantly reduced, PG&E said Wednesday, and may affect about 4,600 in Kern County. Yesterday, the utility said it could impact 46,000 customers.

Both PG&E and city governments were setting up centers that will remain powered, where people can go during daylight to access air conditioning and charging stations.

Some schools close as officials scramble to keep traffic tunnels open

The California Department of Transportation has been working with the utility company to secure backup power generators to keep some traffic tunnels open, including the Caldecott Tunnel in Contra Costa and Alameda counties and the Tom Lantos Tunnel in Pacifica, spokesman Bart Ney told CNN.

The Bay Area Rapid Transit (BART) system isn't expected to shut down, its officials said in a tweet. BART has portable generators at certain stations and will have personnel monitoring the generators, a Twitter thread said.

Some stations may face escalator outages, BART said.

State agencies are working with local governments "to address all emergency management, evacuation and mutual aid needs," the Governor's Office of Emergency Services said.

'Recipe for explosive fire growth'

The National Weather Service has warned of strong winds and low humidity running over dry vegetation, which the service said act as "fuels."

"This is a recipe for explosive fire growth, if a fire starts," the weather service said. "Have your go pack ready."

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The service starting early Wednesday morning issued red-flag warnings for some areas. The warnings mean "warm temperatures, very low humidities, and stronger winds are expected to combine to produce an increased risk of fire danger," the service said.

High temperatures Wednesday are expected to vary widely in the region, from the high 60s in some parts of the Bay Area to the lower 80s elsewhere.