Hundreds of National Guard troops are seen inside the Capitol Visitor's Center to reinforce security on Wednesday. Credit: J. Scott Applewhite / AP

As the House opens its impeachment hearing, the District of Columbia National Guard said it has been authorized to arm troops assigned to security duty on the U.S. Capitol grounds.

The Guard said in a statement that the authority was requested by federal authorities and approved by Army Secretary Ryan McCarthy as of approximately 6 p.m. Tuesday.

Up to 15,000 Guard members are expected to be on duty in coming days in the district to support law enforcement in connection with the Jan. 20 inauguration of President-elect Joe Biden. Authorities are concerned about threats of violence, following the insurrection at the Capitol last week.