Washington, D.C. police say they arrested the leader of right wing nationalists the Proud Boys on Monday (January 4).
The group is expected to converge on the U.S. capital this week as part of broader pro-Trump protests.
Leader Henry "Enrique" Tarrio was charged with destruction of property during an earlier protest and a police statement said he was:
"In possession of two high capacity firearm magazines" at the time of his arrest.
Earlier, Tarrio said on the social media app, Parler, that "record numbers" of members would protest the U.S. Presidential election starting on Wednesday, when Congress is due to certify the election's results.
Last week, President Donald Trump had tweeted:
"The BIG Protest Rally in Washington, D.C., will take place at 11.00 A.M. on January 6th.... StopTheSteal!"
Several rallies are planned, including one outside the Capitol Building. One person briefed on the President's plans said he will speak to his supporters near the White House.
On Monday, city officials warned Trump supporters not to bring guns to the protests. D.C. forbids open carry of weapons or possession of a handgun without a local license.
The D.C. National Guard released a statement saying they've prepared more than 300 troops to support the city government.