The now-national effort has mostly targeted financial institutions, but it has also taken aim at the political system. Hundreds of protesters descended on Washington last week, assembling downtown near the White House and K Street but surprisingly avoiding Capitol Hill until Tuesday.
The protesters entered Hart late on Tuesday morning and occupied several floors before unfurling banners and chanting, staffers and U.S. Capitol Police said. Witnesses said one banner said "Cut Military Spending."
The protest took advantage of Hart's 90-foot central atrium, where upper floors look down on the lobby below.
Witnesses were unsure how many demonstrators were on hand, with estimates ranging from three dozen to 100. Sgt. Kimberly Schneider, a Capitol Police spokeswoman, said six people were arrested and charged with unlawfully demonstrating in a Capitol building. They were being processed at Capitol Police headquarters on Tuesday.
The Hart protest is reportedly just one among several planned for Tuesday near the Capitol.
Hart has not seen the end of protests for the day.
Before the Senate vote on President Obama's jobs plan, SEIU and others are planning a 3 p.m. prayer vigil in the building's atrium. Assembled will be "unemployed workers and their supporters," according to an announcement from organizers.