(CNN) Federal authorities arrested a number of suspected neo-Nazis around the country this week out of concern that they were planning violent acts at Monday's pro-gun rally in Richmond, Virginia, a senior FBI official said Friday.

"A big reason why we disrupted it now was based on the timing of the rally on Monday and the intent of some of the individuals to potentially conduct violent acts down in Richmond," Jay Tabb, the executive assistant director of the FBI's National Security Branch, said at an event put on by the Homeland Security Experts Group in Washington.

Seven men accused of belonging to a white supremacist group called The Base were arrested this week in separate raids in Delaware, Georgia, Maryland, and Wisconsin, according to authorities.

Tabb commended the work of police in Virginia to prepare for the rally, saying that "they are doing everything that they can to make that event and all events around that Monday as safe as possible."

Still, he said, the FBI is concerned.

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