Tens of thousands of people braced for days without electricity in a North Carolina county where authorities say two power substations were shot up by one or more people with apparent criminal intent.

Across Moore County southwest of Raleigh on Monday, businesses handed out free food or coffee, temporary stop signs were erected at intersections where traffic lights went dark and businesses without internet conducted transactions in cash. One local economic official described the area known for its golf courses and local pottery as “eerily quiet” at a time of year when businesses are normally full of tourists and holiday shoppers. County schools were also closed, and a 9 p.m.-5 a.m. countywide curfew was in place.

Meanwhile, federal, state and local authorities were undertaking a massive investigation of what's being described as a serious attack on critical infrastructure. Utility officials said it could take until Thursday to restore all power.

“An attack like this on critical infrastructure is a serious, intentional crime and I expect state and federal authorities to thoroughly investigate and bring those responsible to justice,” Gov. Roy Cooper wrote on Twitter.

On a call with reporters Monday, National Security Council spokesman John Kirby said they were monitoring the attack "very closely."

Kirby said the White House would keep an eye on the investigation into the attack before commenting further, noting that the resilience of things like power grids was a key priority for President Joe Biden, though more needs to be done.

"He's made critical infrastructure security and the resilience of that infrastructure ... he's made it a priority since the very, very beginning," he said. "We still have a long way to go."

Moore County Sheriff Ronnie Fields said Sunday that authorities have not determined a motivation. He said someone pulled up, breached the substation gates and opened fire at the substations. The Pilot newspaper in Southern Pines reported that a wooden post holding up a gate had been snapped at one of the substations and that it was lying in an access road Sunday morning.

He also said the substations were targeted: “It wasn't random."

Fields said law enforcement is providing security at the substations and for businesses overnight.

“We will have folks out there tonight around the clock,” Fields said.

Roughly 35,000 electric customers in the county were without power late Monday morning, down by several thousand from the peak of the outages, according to poweroutage.us. Temperatures dropped below freezing early Monday, and lows in the 40s were expected again later in the week.

About 20 people spent the night at an emergency shelter at the Moore County Sports Complex in Carthage, said Phil Harris, executive director of the local American Red Cross chapter. Harris, who’s managing a team of nine volunteers, said plenty more have stopped by for food, warmth or to charge their devices.

“If you’ve got no power, you probably don’t have any heat, so with winter weather coming in, it’s a nice place to stay,” Harris said.

Duke Energy spokesman Jeff Brooks said Sunday that multiple pieces of equipment were damaged and will have to be replaced. He said while the company is trying to restore power as quickly as possible, he braced customers for the potential of outages lasting days.

“We are looking at a pretty sophisticated repair with some fairly large equipment and so we do want citizens of the town to be prepared that this will be a multiday restoration for most customers, extending potentially as long as Thursday," Brooks said at the news conference.

The county of approximately 100,000 people lies about an hour's drive southwest of Raleigh and is known for golf resorts in Pinehurst and other communities.

The holiday season is one of the busiest times of year for the region's tourism-dependent economy, said Linda Parsons, president of the Moore County Chamber of Commerce.

As they did during the pandemic, businesses that can’t open or lack foot traffic are getting creative with online sales. Some hardware and other stores are doing cash-only transactions, she said. Other businesses are offering free food to residents without power, such as the Southern Pines Growler, which gave out free coffee and pancakes Sunday.

“Our community has done an excellent job coming together ... honestly, it’s quite heartwarming,” she said. “We’re making the best out of a bad situation.”

She said residents of the low-lying area not far from the coast are used to summer weather emergencies such as hurricanes . But this is different, Parsons said: “It’s strangely eerie.”

Andrew Wilkins, a conservation advocate who grew up in Moore County, was driving Saturday night from Washington to his parents’ small farm in Whispering Pines when he noticed the street lights were out in Carthage. He arrived to a “pitch black street” and little information about the cause or scope of the blackout.

“When the power was cut, the flow of information was cut too,” Wilkins told The Associated Press.

He spent the weekend helping his parents link a generator to their well for fresh drinking water and preparing them for cold nights without heat. Local grocery stores, such as Food Lion and Harris Teeter, have been distributing drinks, ice and pantry items to those who lost power, he said.

“Their home, like many rural homes, relies on a well for water for fresh, clean water, and it’s powered by electricity,” Wilkins said. “So when the power went out, the well stopped working, and when the well stops working, we slowly lose pressure until we lose water altogether. People are going to really feel the pinch from this as it goes on.”

Wilkins described Southern Pines as a “tight-knit” and “vibrant” community of military families, farmers and small businesses owners who have been doing all they can to support one another during the power outages. His family’s neighbors, he said, are storing refrigerated medicines for a local pharmacy that lost power.