Four members of a California white supremacist group that prosecutors believe committed particularly violent crimes at the torch-lit march and rally in Charlottesville, Va. last year were arrested, federal authorities said Tuesday.

The four men -- Benjamin Drake Daley, Michael Paul Miselis, Thomas Walter Gillen and Cole Evan White – are accused of violating or conspiring to violate the Riots Act and face up to 10 years in prison for their actions in Virginia last year.

“This wasn't, in our view, the lawful exercise of First Amendment rights. These guys came to Charlottesville in order to commit violent acts, and it wasn't the first time they've done it,” U.S. States Attorney Thomas T. Cullen said in a news conference Tuesday, adding that additional charges, including hate crimes, could be added.

Prosecutors accuse the four men of being part of the Rise Above Movement, which espouses anti-Semitic views and meets regularly in public parks to train in boxing and other fighting techniques, according to an affidavit.

Gillen made an initial court appearance Tuesday in California. He wore a blue T-shirt, chewed gum and yawned several times as his detention hearing was waived until Thursday.

When Judge Jean Rosenbluth asked Gillen if he understood what the government was accusing him of, Gillen said, "For the most part, yeah." When pressed further, Gillen responded: "I generally understand what I'm being charged with, your Honor."

The arrests come more than a year after a deadly riot broke out when hundreds of white nationalists descended on Charlottesville to protest the planned removal of a statue of Confederate General Robert E. Lee.

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The men traveled from California to Virginia to participate in the two-day white nationalist rally that turned deadly. Prosecutors said they traveled with the purpose of inciting a riot and attacking counterprotesters.

Members of white nationalists rally around a statue of Robert E. Lee in Charlottesville, Va., Aug. 12, 2017. (Reuters)

The affidavit alleges that the four men were "among the most violent individuals present in Charlottesville" on Aug. 11 and 12 of last year. It says photos and video footage shows they attacked counterprotesters, "which in some cases resulted in serious injuries."

The men have also taken part in "acts of violence" at political rallies in Huntington Beach and Berkeley, Calif., and other places, the affidavit alleges.

During the rally, a woman was killed when a car that prosecutors said was driven by a man fascinated by Adolf Hitler plowed into a crowd of peaceful counterprotesters. The death toll jumped to three when a state police helicopter that had been monitoring the event crashed, killing two troopers.

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The suspected driver, 21-year-old James Fields Jr., of Maumee, Ohio, has been charged with federal hate crimes in the death of Heather Heyer, 32. Fields also faces state murder charges. His trial is scheduled to begin Nov. 26.

President Donald Trump sparked a public outcry after he blamed both sides for the violence last year.

The rally was believed to be the largest gathering of white nationalists in at least a decade. An independent report released three months later found serious police and government failures in responding to the violence.

The Associated Press contributed to this report.