The FBI joined state and local law enforcement officials to investigate deliberate attacks on two power substations in North Carolina.
Shelley Lynch, a spokesperson for the FBI field office in Charlotte, told The Washington Post that agents are on the ground at the substations in Moore County. They're investigating the "willful damage" of power systems brought down by gunfire on Saturday night. She declined to provide further details.
Duke Energy personnel inspect power systems damaged by bullets.
About 36,000 customers of Duke Energy in southeastern North Carolina were without power early Tuesday morning. Officials estimate service repairs could take several days to complete.
A state of emergency was declared over the weekend, with a countywide curfew from 9 pm to 5 am. Schools will remain closed for a second day.
North Carolina Governor Roy Cooper told reporters in a news briefing on Monday, "this kind of attack raises a whole new level of threat." He added safeguarding critical infrastructure must be a "top priority."
"The person, or persons, who did this knew exactly what they were doing ... not sure why they targeted Moore County," Sheriff Ronnie Fields said at a news conference on Sunday.
Fields said the FBI was working with local authorities to determine who was responsible, adding someone rode up and "opened fire on the substation, the same thing with the other one." There was no word on the type of weapon or caliber used in the incident.