NORTH CAROLINA, United States (AP) — Two power substations in a North Carolina county were struck by gunfire in what is being investigated as a criminal act, causing damage that could take days to repair and leaving tens of thousands of people without electricity, authorities said.

In response to ongoing outages, which began just after 7:00 pm Saturday across Moore County, officials announced a state of emergency that included a curfew from 9:00 pm Sunday to 5:00 am Monday. Also, county schools were closed Monday.

“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,” Governor Roy Cooper wrote on Twitter.

Moore County Sheriff Ronnie Fields said at a Sunday news conference that authorities have not determined a motive. He said someone pulled up and “opened fire on the substation, the same thing with the other one”. The sheriff said that it appeared gates were breached at both sites. 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.

“No group has stepped up to acknowledge or accept that they’re the ones that done it,” Fields said, adding “we’re looking at all avenues.”

The sheriff noted that the FBI was working with state investigators to determine who was responsible. He also said “it was targeted”.

“It wasn’t random,” Fields said.

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

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

Roughly 35,400 electric customers in the county were without power on Monday morning, down by several thousand from the peak of the outages, according to PowerOutage.us.

With cold temperatures Sunday night the county also opened a shelter at a sports complex in Carthage.

Duke Energy spokesman Jeff Brooks said 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 multi-day restoration for most customers, extending potentially as long as Thursday,” Brooks said at the news conference.

Dr Tim Locklear, the county’s school superintendent, announced classes were cancelled Monday.

“As we move forward, we’ll be taking it day by day in making those decisions,” Locklear said.

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

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 all the street lights were out in the county seat of 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 neighbours, he said, are storing refrigerated medicines for a local pharmacy that lost power.