Over a dozen Utah-based white supremacists have been indicted on drug and firearms charges.

The charges arrived after an investigation was launched in June 2019, directed at the Soldiers of Aryan Culture, Silent Aryan Warriors, Noble Elect Thugs, and associates, NPR reports. Bureau of Alcohol, Tobacco, and Firearms and two gang units were involved with the probe.

The defendants have been characterized as “documented gang members and associates of several home-grown white supremacist gangs” from the Salt Lake City and Ogden areas.

“SAC and SAW are highly volatile, dangerous criminal enterprises,” Mike Schoenfeld, director of the Salt Lake Area Gang Project, said Friday. “These gangs have their roots right here in the Utah prison system. It’s not something to be proud of. But they also have very strong ties nationwide to other violent white supremacy groups.”

The Justice Department said 11 people were arrested on Wednesday after 10 others were already in custody. Charges include distributing heroin and methamphetamine, possessing a firearm while selling drugs, and having a gun as a felon.

“The investigation led law enforcement officers to numerous documented gang members and associates trafficking in methamphetamine and firearms,” a statement said. “Many of the defendants have been involved in criminal conduct in Utah communities for many years.”

The FBI has expressed its concern about the growth of right-wing extremist groups and white supremacy. Last month, Director Christopher Wray testified before the House Homeland Security Committee, telling lawmakers that “racially motivated violent extremism”—or white supremacists—have comprised most of the U.S.’s domestic terrorism threats.