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Nearly 90,000 utility customers in Los Angeles County were without power Sunday night amid scorching hot temperatures after electricity was restored for several thousand others, officials said.

The Los Angeles Department of Power reported 70,000 customers experiencing outages and Southern California Edison had 18,629 customers without power in L.A. County alone.

The California Independent System Operator, which runs the electrical grid for most of the state, said Sunday that rotating power outages are “likely” as the heat wave was expected to bring record-breaking demand for energy that could strain the state’s power grids.

But the agency later said the state mostly avoided rolling blackouts through residents’ energy-saving efforts.

Many LADWP customers hit by outages live in Koreatown, Highland Park, Mid Wilshire, Reseda, Harvard Heights and Green Meadows, the agency said. Utility officials have said it could take 24 to 48 hours for crews to restore power.

“Crews will be working throughout the night and around the clock to restore power as quickly and safely as possible to affected customers,” LADWP said in a statement.

Extreme heat throughout Southern California hit LADWP’s power distribution in many L.A. neighborhoods, overwhelming circuits and equipment, the utility said.

LADWP said power has been restored for 77,000 of its customers since extremely hot temperatures began straining the state’s electrical grids on Saturday. The agency has asked customers to set their air conditioners to 78 degrees or higher to help power grids recover.

Glendale Water and Power started having rolling blackouts around 3 p.m., warning that affected customers could be without power for an hour. By 3:40 p.m., the utility said all power was restored to the customers affected by rolling outages but urged residents to conserve energy.

Edison reported more than 28,000 of its customers statewide were without power due to heat-related outages. Another 2,500 lost power due to Creek Fire in Central California.

Earlier Sunday, the utility said a total of 47,500 customers across the region lost electricity.

Californians were under a statewide Flex Alert, with electrical grid operators urging residents to reduce their power consumption from 3 p.m. to 10 p.m. each day through Monday.