RIDGEWAY, S.C. (AP) — Law enforcement officials say they have found no evidence linking gunshots near a Duke Energy facility in South Carolina to earlier gunfire at North Carolina electric substations that cost thousands of customers their power, though multiple state and federal agencies continue to investigate.

Kevin Wheeler, a spokesperson for the Federal Bureau of Investigation in Columbia, South Carolina, said that while “no stone is left unturned,” there is no information connecting the Wednesday’s incident in South Carolina to Saturday’s in North Carolina.

A firearm was discharged from a speeding vehicle Wednesday evening on the opposite side of a road located about half a mile away from a Wateree Hydro Station in Ridgeway, South Carolina, Kershaw County Sheriff Lee Boan said in a Thursday afternoon post on the office’s Facebook page.

“We currently have no evidence leading us to believe this incident involves any type of attack on the Duke Energy Hydro Station,” Boan said in the post. “The shooting appears to be a random act and the only connection between the shooting and the hydro station is their proximity.”

Duke Energy said it found no sign of property damage, reported outages or harmed individuals. But heightened concern after one or more people drove up to two North Carolina substations, breached the gates and opened fire on Saturday night has prompted a joint investigation between South Carolina law enforcement officials and the FBI, according to Boan.

Boan told WLTX-TV that a deputy went to the hydro station, where people reported that someone fired from the passenger side window of a vehicle that went by. The witnesses said the shooter fired toward the woods nearby, not at them or the power plant or dam, “so we can’t absolutely confirm that there was any threat to the power station,” Boan said.

A spokesperson for the U.S. Department of Energy said it also is investigating the gunfire.

“DOE strongly condemns these attacks and will continue to work with law enforcement and our partners to address these threats and secure our nation’s critical energy infrastructure,” a statement read.

Duke Energy completed repairs Wednesday on electric substation equipment that was damaged in the North Carolina shootings, knocking out power to more than 45,000 customers. Officials said power was restored to the county Wednesday evening, though the effects of the outage were still being felt Thursday in Moore County, where schools remained closed.

No motive has been released in the North Carolina attacks, but Moore County Sheriff Ronnie Fields told reporters that whoever was responsible “knew exactly what they were doing to … cause the outage that they did.”

The FBI posted a notice seeking tips, and North Carolina, Moore County and Duke Energy have offered combined rewards of up to $75,000 for information leading to an arrest and conviction.

Electric utilities in the Northwest U.S. have also reported attacks on the electrical grid in recent weeks.

At least four electrical substations have been targeted in separate attacks in Oregon and Washington since late November, Oregon Public Broadcasting and KUOW Public Radio reported Thursday. Attackers used firearms in at least some of the incidents, and some power customers in Oregon temporarily lost service.

In one of the attacks, two people cut through a fence surrounding a high-voltage substation and then shot several pieces of equipment, according to an email from Bonneville Power Administration security specialist Kenneth Worstell. Worstell also referenced several other recent attacks that included setting control houses on fire, sabotaging electrical control systems and intentionally causing short circuits.

The utilities — Portland General Electric, the Bonneville Power Administration and Puget Sound Energy — said they were working with the FBI on the attacks. The FBI declined to confirm the investigation.

“The FBI routinely shares information with our law enforcement partners in order to assist in protecting the communities they serve,” Joy Jiras, a spokeswoman for the FBI in Portland, Oregon, said in a statement to the broadcast stations on Wednesday. “We urge the public to remain vigilant and report any suspicious activity to law enforcement.”

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A previous version of this story misspelled the name of a local news station. The correct identification is WLTX-TV.