Dallas Humber, 34, of Elk Grove, California, and Matthew Allison, 37, of Boise, Idaho, each face 15 criminal counts, including soliciting hate crimes and providing material support to terrorism. The two were in custody, officials said; it was not immediately clear if they had lawyers.

The group's targets also included U.S. government officials and critical infrastructure sites, with an overall goal of causing societal collapse in the United States, U.S. Justice Department officials said during an online news conference.

"The federal government is adapting and evolving its strategy to confront hate," said Kristen Clarke, the head of the Justice Department's Civil Rights Division. "Whether carried out on our streets or perpetrated by way of online platforms, we will follow the facts where they lead and use every tool available to hold perpetrators of hate accountable."

Humber and Allison helped create and promote a document that sought to justify the group's ideology and included detailed instructions on carrying out terror attacks, including how to build bombs, according to the indictment.