Two men have been charged with federal crimes for attacking substations in Washington State, an act of sabotage that left thousands without power on Christmas Day.

Federal agents say one of the men confessed to knocking out the power in order to commit a burglary by emptying the cash register of a local business during the power outage.

The FBI says cell phone records led to the arrest of Matthew Greenwood, 32, and Jeremy Crahan, 40, both residents of Puyallup, Wash. According to documents unsealed Tuesday, both men have been charged with conspiracy to damage energy facilities, and Greenwood has also been charged with possession of an unregistered firearm.

The sabotage came after a string of other attacks on power infrastructure across the U.S., including one that caused a major outage in North Carolina.

The Department of Homeland Security has previously warned that power infrastructure is an "attractive" target for domestic terrorists; however, the charging documents for Greenwood and Crahan don't indicate any political motivations.

"We have seen attacks such as these increase in Western Washington and throughout the country and must treat each incident seriously," U.S. Attorney Nick Brown said in a statement. "The outages on Christmas left thousands in the dark and cold and put some who need power for medical devices at extreme risk."

A public defender assigned to Matthew Greenwood declined to comment, while the lawyer appointed to defend Jeremy Crahan says he expects to enter a not guilty plea.

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