Washington (CNN) -- At least eight people were arrested Thursday by U.S. Capitol police after demonstrating outside a room in the Rayburn House Office Building, police said.

One of the protesters was charged with simple assault and seven were charged with disruption of Congress, authorities said.

The demonstration started when California Republican Howard P. "Buck" McKeon, chairman of the House Armed Services Committee, was delivering opening statements in a defense hearing Thursday.

At least some of the protesters were from a group called "Code Pink," which regularly disrupts high-profile congressional hearings dealing with war and national defense issues.

The arrests come as demonstrations against corporate greed and social inequality take place in cities nationwide.

Earlier this week, a crowd of about 100 people protested outside the White House, while others have gathered in front of the U.S. Chamber of Commerce.