Wildfire danger spread from northern California to the south of the state, as a blaze swept through the San Fernando Valley’s northern foothills and concerns rose that a utility company could order further power shutoffs.

Southern California Edison turned off electricity to about 20,000 people in Los Angeles, Ventura, San Bernardino and Kern counties on Friday but warned that thousands more could lose service as Santa Ana winds gained strength.

A wildfire fueled by Santa Ana winds broke out in Los Angeles, forcing the closure of several highways because of heavy smoke. The so-called Saddleridge fire, which started in Sylmar, had consumed more than 7,500 acres by 5pm local time Friday, prompting California’s governor, Gavin Newsom, to declare a state of emergency.

Officials said a middle-aged man died near where the fire was burning after he went into cardiac arrest and that a firefighter suffered an eye injury.

Authorities also ordered mandatory evacuations of about 100,000 people in the Granada Hills, Porter Ranch and Oakridge Estates neighborhoods. Several homes were seen burning in Granada Hills, and the Los Angeles fire department said an “unknown number” of homes were potentially threatened.

NOW on @NBCNightlyNews: @GadiNBC is on the ground in Los Angeles, where a fast-moving wildfire has exploded in size, damaging homes and prompting evacuations. https://t.co/kvnatgjbFp https://t.co/NajJd7qNU5 — NBC Nightly News with Lester Holt (@NBCNightlyNews) October 11, 2019

A blaze also ripped through a mobile home park in Calimesa, a city about 65 miles (104km) east of Los Angeles, destroying dozens of residences. The fire started when trash being hauled caught fire and the driver dumped the load beside a road, according to Riverside county officials. An 89-year-old woman, Lois Arvickson, died while on the phone with her son.

In northern California, the utility company PG&E started restoring power to some of the communities that were cut off on Wednesday and Thursday. PG&E had shut off power to an estimated 2 million people in northern California over fears its equipment could spark wildfires amid high winds.

Red flag fire warnings are expected to continue in southern California through Saturday.

Firefighters try to protect surrounding homes as they battle the Sandalwood fire in Calimesa, California, on 10 October. Photograph: Jennifer Cappuccio Maher/AP

Newsom criticized PG&E on Thursday, and customers complained about the inconveniences caused by the unprecedented blackouts that began midweek.

Newsom told reporters PG&E’s decision to cut power should not be blamed on the climate crisis. Instead, he said he believed the blackouts were the result of mismanagement, “greed and neglect” by the nation’s largest investor-owned utility.

“What has occurred in the last 48 hours is unacceptable,” Newsom said, listing problems such as school closures and people who “can’t even access water or medical supplies”.

“Northern California is not a third world country,” the San Jose Mercury News said in an editorial. “It’s unacceptable that the region is being forced to endure this level of disruption as the long-term strategy for dealing with the threat of wildfires.”

PG&E suggested it was already seeing the wisdom of its decision borne out as gusts topping 77mph (122km/h) raked the San Francisco Bay Area amid a bout of dry, windy weather.

“We have found multiple cases of damage or hazards” caused by heavy winds, including fallen branches that came in contact with overhead lines, said Sumeet Singh, a vice-president for the utility. “If they were energized, they could’ve ignited.”

PG&E began practicing preventive shutoffs this year during red flag fire weather conditions – high winds and low humidity – after investigators found it at fault in two of the deadliest wildfires in California’s history, both within the past two years.

Some of the wildfires started because of trees falling on power lines – trees that should have been cleared by PG&E because of their proximity to the lines. In the 2018 Camp fire, the utility’s outdated infrastructure was implicated. The Camp fire, which killed 85 and virtually incinerated the town of Paradise, was blamed on PG&E transmission lines.

PG&E’s CEO, Bill Johnson, promised the utility will “do better” when it comes to communicating with customers during future shutoffs. It was unacceptable that its websites crashed, maps were inconsistent and call centers were overloaded, Johnson said.

“We were not adequately prepared,” he said.

Faced with customer anger, PG&E put up barricades around its San Francisco headquarters. A customer threw eggs at a PG&E office in Oroville. And a PG&E truck was hit by a bullet, though authorities could not immediately say whether it was targeted.