(NewsNation) — Thousands in a North Carolina county are still without power Monday after what authorities are calling a targeted attack on two power substations, police said.

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

Moore County Sheriff Ronnie Fields said the substations were damaged by gunfire in what is being investigated as a criminal act. He said the damage could take days to repair, leaving thousands of people without electricity.

“All of a sudden without any sign of a storm or wind or anything, the lights just went dark,” a community resident told reporters.

At a Sunday news conference, Fields said 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.

“Folks, we’re living in some challenging times,” Fields said during the press conference. “Challenging times that I’ve never thought in my 40 years in law enforcement.”

North Carolina Sen. Tom McInnis also attended the news conference, saying, “The perpetrator will be brought to justice and prosecuted to the fullest extent of the law.”

Fields said that no group or individual has stepped up to acknowledge or accept that they have committed the crime.

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 at the substations and for businesses overnight.

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

Roughly 36,100 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.

A community grocery store is running on backup generators and has become a place to charge phones and computers. The store has also been handing out free bags of ice to the community, NewsNation affiliate WNCN reported.

A local pizza shop is also helping out by using its one gas oven to feed those in the nearby community, despite not having any electricity either, WNCN reported.

Shelters have opened across the county, according to a report from CNN.

The Associated Press and NewsNation affiliate WNCN contributed to this report.