The U.S. Capitol is reported to be on a security lockdown after shots apparently were fired outside the building.
U.S. Capitol police report at least one person wounded in the shooting. The victim has been identified as a Capitol police officer.
In a notice sent by email, Capitol police advised people inside all House of Representatives office buildings to "close, lock and stay away from external doors and windows."
VOA congressional correspondent Cindy Saine said some members of Congress were locked inside the House chamber.
The Senate has halted all business for the time being.