A Neo-Nazi leader and his girlfriend hoped to lay “waste” to Baltimore by attacking multiple electrical substations, Justice Department officials said.

Federal prosecutors today announced charges against Florida resident Brandon Clint Russell, an alleged leader of a Neo-Nazi group called Atomwaffen Division, and Sarah Beth Clendaniel of Maryland, saying the two conspired to destroy an energy facility.

“The FBI believes this was a real threat,” Thomas Sobocinski, special agent in charge of the bureau’s Baltimore field office, told reporters during a press conference today. Clendaniel bragged that the attack “would lay this city to waste,” Sobocinski said.

Russell plotted from at least last June “to carry out attacks against critical infrastructure, specifically electrical substations, in furtherance of Russell’s racially or ethnically motivated violent extremist beliefs,” according to a statement by the US Attorney’s office in Baltimore.

Prosecutors noted that Russell was sentenced in January 2018 to five years in prison for possessing an illegal destructive device discovered during the investigation of the murder of two of his roommates. Russell admitted founding Atomwaffen Division and said the two murder victims were also members of the group. The killer, a third roommate, said the others were planning to attack a Florida nuclear power plant and other critical infrastructure.

The Justice Department today didn’t say or present evidence that Russell and Clendaniel’s plot was connected to any group. Initial court appearances are scheduled for Clendaniel today in Baltimore and for Russell today in Orlando, Florida.

Lawyers for the two couldn’t immediately be identified.

The plot is the latest in a string of attacks or plans to destroy or damage electrical plants or power substations around the US. Such attacks rose to an all-time high last year, jumping 77% incidents, including acts of vandalism and other suspicious activity, in more than three dozen states, according to information from the US Energy Department released last week.

In December, up to 45,000 North Carolina customers were left in the dark after two of Duke Energy Corp.’s substations were damaged by gunfire while another attack on four stations in Washington state cut power to more than 15,000 people and caused $3 million in damage.