LOS ANGELES (CBSLA.com) — Triple-digit heat continued to scorch the Southland Monday, straining Southern California Edison as scattered power outages plagued the region.

An excessive heat warning was extended for the San Gabriel, San Fernando and Santa Clarita valleys through 7 p.m. Tuesday.

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“Due to an influx of moisture from Northern Mexico, heat index values will continue to reach critical levels across parts of Los Angeles and Ventura counties Monday through Tuesday,” the National Weather Service said.

As of 10 p.m., more than 6,600 SCE customers in L.A. County were impacted by power outages.

SCE’s Vice President of Transmission, Substations and Operations Paul Grigaux urged customers to conserve energy whenever possible as crews worked to restore electrical service to those affected late into the evening.

“We anticipate having an adequate supply of electricity,” Grigaux said in a press release. “However, with more energy likely being used in the evenings, especially air conditioning, the extra demand can strain SCE’s equipment when it’s not given the opportunity to cool off.”

KCAL9’s Serene Branson reported Monday evening from Long Beach, where local resident Curtis Bronzan remained without power while several of his neighbors saw theirs restored.

“We have a 3-and-a-half-year-old and an 11-month-old, so it is difficult trying to keep milk cold,” he said, adding that the family is now staying with a friend.

Bronzan said a SCE representative told him the outage may have disrupted a circuit breaker, which is up to him to fix. He intends to file a claim.

In Corona, CBS2’s Crystal Cruz reported residents were struggling to deal with outages, some going more than 24 hours without power.

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“We have two refrigerators and two freezers full of food. A bunch of hungry kids… it’s just been a terrible two days,” one local woman said.

The Department of Water and Power also reported several scattered outages for their customers across the San Fernando Valley. LADWP officials said Monday’s all-time record doubled the city’s demand on a typical day, with another record expected to be set Tuesday.

The hot temperatures were also making it difficult for firefighters battling the Silverado Fire in the Silverado Canyon of the Cleveland National Forest. As of Monday evening, the fire, which had torched 968 acres, was 87 percent contained.

KCAL9’s Kristine Lazar reports the Los Angeles Unified School District has canceled all outdoor activities for students both Monday and Tuesday. After-school sports held outdoors are also canceled.

“Our primary goal is to make sure all the kids stay safe and hydrated. So we want to make sure they are indoors as much as possible [and] that they’re not exerting themselves,” said Kelly Hanock, principal of the Valley Academy of Arts and Sciences in Granada Hills, where the temperature read 109 degrees on the school’s marquee Monday afternoon.

Officials encourage residents to drink plenty of water and remain inside with air-conditioning.

For a list of Cooling Centers and information on heat-related illnesses and prevention, visit the Public Health website or call the L.A. County Information line at 2-1-1 from any landline or cell phone within the county.

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For information about how you can report an outage and conserve power, visit the SCE website.