Hundreds of National Guard troops are stationed inside the Capitol Visitor’s Center to reinforce security at the Capitol in Washington on Wednesday. J. Scott Applewhite/Associated Press

Another 5,000 members of the National Guard have been authorized to support Inauguration Day security in Washington, D.C., city officials said Wednesday, increasing the total to at least 20,000 in a rapidly swelling security apparatus focused on the Capitol.

“I think you can expect to see somewhere upwards beyond 20,000 members of the National Guard that will be here in the footprint of the District of Columbia,” acting D.C. police chief Robert Contee said at a news conference.

A defense official, speaking on the condition of anonymity, said that Pentagon officials were still working through plans for providing additional security support to the inauguration.

The official said that a discussions with city and federal officials over the final number of National Guard that will be sent into Washington were still at a notional stage, as officials plan for what is needed and take part in tabletop exercises led by the Secret Service.

For now, officials say 10,000 will be in place by the weekend. National Guard forces in and around the Capitol will be armed, while others are expected to be unarmed.

Defense Department officials are scrambling to establish an adequate plan for providing National Guard aid for the inauguration and avoid a repeat of last week’s attempted insurrection at the U.S. Capitol.