Power is being shut off to nearly 800,000 Pacific Gas and Electric customers in California due to the threat of wildfires, according to Weather.com.

Schools and universities were closed in some areas and residents stocked up on groceries, batteries and gas ahead of the blackouts, which PG&E said could last as long as five days.

Some 520,000 homes and businesses in northern California were already without power as of 4:30 p.m. PDT Wednesday (Oct. 9), according to poweroutage.us. PG&E’s website had crashed due to high traffic.

The preemptive outage stands to be one of the largest in the state’s history as windy, dry conditions raise the risk for wildfires in the coming days. Many of those affected are in the San Francisco Bay area and the northern part of the state, including San Jose, Oakland, Fremont, Santa Rosa, Hayward, Berkeley and San Mateo.

The shutoffs started at 12 a.m. PDT Wednesday morning, with the first phase expected to impact about 500,000 customers in 22 counties, PG&E said in a news release.

A second phase was expected to start at noon with another 230,000 customers affected, but PG&E announced that the shutoffs would be delayed until later in the day. A third phase covering about 40,000 customers is also being considered.

In all, parts of some 34 counties in northern, central and coastal California face blackouts. The utility said the shutoffs were being considered based on a fire weather watch from the National Weather Service (NWS). Winds up to 65 mph were expected in some areas, prompting the NWS to issue alerts for elevated, critical and extreme wildfire chances across large swaths of the state.

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