The Bobcat Fire was advancing at a mile or two an hour at times and continued to threaten the Mojave Desert town of Pearblossom after burning into the Antelope Valley foothill area, on the other side of the San Gabriel Mountains from Los Angeles.

The blaze that began Sept. 6 destroyed or damaged at least 29 homes and other buildings, including some in the Juniper Hills area, with the toll rising to perhaps 85 when damage assessment teams can complete their work this week, authorities said.

Firefighters also battled flareups near Mount Wilson, which overlooks greater Los Angeles and has a historic observatory founded more than a century ago and numerous broadcast antennas serving Southern California.

The fire was fueled by vegetation that hadn’t burned in decades and pushed by erratic winds over the weekend, although they had died down by Monday, and were expected to remain light through Tuesday.

Near Mount Wilson, firefighters set more than a mile of fires designed to burn out the blaze’s fuel and act as a brake on its advance.

However, with the fire only about 15% contained, firefighters weren’t taking anything for granted.

“We’ve got a fire here that is bigger than the city of Denver, and it did it in two weeks,” said Sky Cornell with the Los Angeles County Fire Department.

About 1,100 homes and some 4,000 residents remained under evacuation orders, fire officials said Monday evening.

Evacuation warnings — meaning residents should be prepared to flee if ordered — remained in effect for the LA suburb of Pasadena, home of the Rose Bowl and the annual Rose Parade, and Wrightwood, a mountain community near several San Bernardino County ski resorts.

The blaze was one of more than two dozen major wildfires burning across California, including five of the largest in state history.

More than 5,600 square miles (14,500 square kilometers) have been charred, an area larger than the state of Connecticut, and at least 23,00 people remain evacuated statewide, Gov. Gavin Newsom said.

Early estimates are that 6,400 buildings have been destroyed across the state, but Newsom said “by no stretch of the imagination do we think this tells the entire story.” Damage assessments are ongoing, he said, AP reported.

Numerous studies in recent years have linked bigger US wildfires to global warming from the burning of coal, oil and gas, especially because climate change has made California much drier. A drier California means plants are more flammable.

Nearly 19,000 firefighters in California are currently battling 27 major blazes, Newsom said. At least 7,900 wildfires have erupted in the state this year, many during a mid-August barrage of dry lightning that ignited parched vegetation.

Twenty-six people have been killed. Officials were investigating the death of a firefighter at another Southern California wildfire that erupted earlier this month from a smoke-generating pyrotechnic device used by a couple to reveal their baby’s gender.

Charles Morton, 39, died on Sept. 17 while battling the El Dorado Fire in San Bernardino National Forest about 75 miles (120 kilometers) east of Los Angeles.

Morton, was a 14-year veteran of the US Forest Service and a squad boss with the Big Bear Interagency Hotshot Crew of the San Bernardino National Forest.

“Charlie was a well-respected leader who was always there for his squad and his crew at the toughest times,” said US Forest Service Chief Vicki Christiansen.

“Charlie is survived by his wife and daughter, his parents, two brothers, cousins, and friends. He’s loved and will be missed. May he rest easy in heaven with his baby boy,” Morton’s family said in a statement.

In Wyoming, officials warned that “a high probability for fire growth” exists for a blaze burning toward cabins and an important water supply reservoir that’s a major source of water for the state’s capital city, Cheyenne. The Mullen Fire in the Medicine Bow National Forest is burning in heavily forested, rugged terrain that would usually be busy now with hunters at the start of elk hunting season.

And in Colorado, one of the state’s largest wildfires continued to grow slowly, with firefighters benefiting as the flames spread into flatter ground Monday. Still, the Cameron Peak Fire near Red Feather Lakes had covered 162.7 square miles (421.39 square kilometers) and was just 15% contained. At higher elevations, it devoured many lodgepole pine trees killed by a beetle infestation.

More than 9,000 firefighters continue to battle large wildfires across Oregon and Washington, where thousands of residences have been destroyed, the Pacific Northwest Region of the Forest Service said.

The California Independent System Operator, which oversees the state grid, declared a Stage 3 emergency late on Friday, initiating the outages that impacted about 750,000 homes with demand soaring from people blasting fans and air-conditioners to keep cool.

Record high temperatures were seen around the Bay Area, according to the National Weather Service, with San Francisco reaching 35 deg C and San Jose 39.4 deg C.

The intense heat is hitting at an especially vulnerable time for the region, with the pandemic forcing people to remain at home.

It’s the first time the state has declared a Stage 3 emergency since electricity shortages pushed hundreds of thousands in the region into darkness, forced California’s largest electric utility into bankruptcy and sent power prices surging to record levels in 2000 and 2001.

About half of the customers were affected as of 8.15pm local time, according to PowerOutage.us, which tracks power shutdowns.

California grid operators decided to call for the rotating outages around 6.30pm local time when they determined through a complex calculation that the state’s power reserves had fallen below a critical threshold, said Ms. Anne Gonzales, a spokesman for the California ISO.

“We had an energy shortfall,” Ms. Gonzales said in a phone interview. The state needed to reduce demand by about 1,000 megawatts, she said. That’s equivalent to the amount of power supply for about 750,000 homes, according to the California ISO, Bloomberg reported.

The bulk of the outages came from PG&E Corp. The state’s biggest utility said it expected as many as 250,000 customers to be shut off in rolling outages, with power to be fully restored by 11 pm. Customers in El Dorado and San Mateo counties were the first to be impacted, said Mr. Jeff Smith, a company spokesman.

“Unfortunately, because of the emergency nature of this, we weren’t able to notify customers in advance,” Mr. Smith said in a telephone interview. The outages occurred for 60 to 90 minutes on a rotating basis through the utility’s Northern and Central California service territory, he said.

Edison International’s Southern California Edison utility began shutting off customers shortly before 7 pm, with about 132,000 of them without power as of 7.45 pm, said spokesman David Song.

The company planned to rotate the blackouts through blocks of customers, trying to ensure no one stayed without electricity for more than an hour in the outages through 10 pm. “It’s happening pretty fast,” he said.

Sempra Energy’s San Diego Gas & Electric utility said shut-offs were “widespread” across its territory in San Diego and southern Orange counties, affecting about 58,700 customers whose power was restored as of 8 pm, an hour, and 20 minutes after the outages started.

“The California ISO is working closely with California utilities and neighboring power systems to manage the strain on the grid and to restore the power grid to full capacity,” the agency said in a statement on Friday.

California is joining regions around the world that have been grappling with extreme weather brought on by climate change in recent months. What was forecast as one of the worst heat waves in more than a century gripped parts of Europe in August? The eastern US is just emerging from July temperatures that were expected to topple daily records in Manhattan and Boston dating to the 19th century.

The rolling outages in California also come less than a year after utilities in the region deliberately cut off power to millions of customers in an effort to prevent their power lines from igniting wildfires amid unusually strong winds – another consequence of increasingly extreme weather that has led to fires across the state in the past week.

California won’t see a respite from the high temperatures until later next week as the National Weather Service forecasts a long-duration heat wave starting this weekend. The weather agency posted excessive heat warnings for much of California for Friday through Wednesday.

Electricity prices have already hit two-year highs as weather forecasters called for extreme temperatures. Spot power prices surged past US$1,000 (S$1,370) a megawatt-hour across California on Friday evening.

Natural gas prices in Southern California more than doubled on the increased need for fuel for power production, according to a report from BloombergNEF.

Grid operators will continue to monitor the situation throughout the weekend and into next week, Ms. Gonzales said. Asked whether the California ISO will need to call for additional power shut-offs, she said: “We don’t expect one, but we are prepared for one.”

The Lake Fire erupted at around 3:30 pm (2230 GMT) near Lake Hughes, about a 90-minute drive from Los Angeles, prompting neighborhood for evacuation.

Rapidly-spreading flames had scorched some 10,000 acres (4,050 hectares) within a little more than three hours, according to the Los Angeles County Fire Department.

“Multiple agencies are battling a brush fire near the Lake Hughes area in the Angeles National Forest,” the department said in a tweet, AFP reported.

The smoke plume from the flames could be seen miles away from the site of the fire.

More than 300 firefighters backed by helicopters and fixed-wing aircraft were deployed to fight the blaze.

“#LASD deputies currently evacuating residents in the area,” the fire department said in another tweet, referring to the LA Sheriff’s Department. “Please help us help you & our loved ones get out safely.”

Wildfires have become more frequent and bigger in California in recent years, in part driven by climate change.

The deadliest fire in the state’s history – the Camp Fire – took place in northern California in November 2018 and killed 86 people.

The two deceased people and the four injured ones were treated at St Elizabeth Community Hospital in Red Bluff, spokeswoman Allison Hendrickson told AP. She declined to provide more details. Red Bluff is a city of about 14,000 people about 210km north of Sacramento, California.

The shooting by a man with “AR-type weapon” started about 3.30 pm at the Walmart distribution center south of Red Bluff, emergency dispatchers told the Record-Searchlight newspaper.

There also was a fire at the site, and the suspect appears to have rammed a vehicle into the building, dispatchers said. There were about 200 workers inside the facility, some of whom locked themselves in a room, employees at the center told the KHSL TV station.

The suspect was described as being in a white vehicle that had wedged into the building, the Sacramento Bee reported. The shooter was in the middle of the parking lot, dispatchers said.

The suspect had been shot in the chest by about 3.45 p.m., dispatchers told the newspaper.

Scott Thammakhanty, an employee at the facility’s receiving center, said he heard the shooter fire from a semi-automatic weapon.

“It went on and on — I don’t even know how many times he fired,” Thammakhanty said. “I just know it was a lot.”

Thammakhanty and others started running for their lives, and he saw people lying on the ground as he went, he said.

Thammakhanty told the newspaper that he didn’t know his identity.

Fellow employee, Franklin Lister, 51, told the New York Times he had just started work when a coworker ran down the hallway shouting: “Active gunfire! Active shooter!”

Dispatchers told the Record-Searchlight that at least one woman had been shot. A man had also reported his leg getting run over when the shooter rammed a vehicle into the store, but the man wasn’t sure whether he’d been shot, dispatchers said.

Walmart spokesman Scott Pope told the Record-Searchlight that the company is “aware of the situation” and working with law enforcement.

“We don’t have any additional information to share at this time,” Pope said.