The Senate has sent out a message to staff: A "suspicious package" is being investigated by Capitol Police in one of the Senate office buildings.
"The U.S. Capitol Police are responding to a suspicious package on the Atrium of the Hart Senate Office Building. All staff and other personnel are directed to avoid this area until further notice," the alert reads.
The subject of the email message reads, "Important message from U.S Capitol Police."
However, one Senate aide responded by saying, "It appeared to be business as usual in the Capitol, with senators debating the gun bill."
UPDATE: Politico says a bomb squad is on hand at the Hart building, and also the Russell office building:
BREAKING: Bomb squad on the scene at Hart and Russell Senate office buildings #BreakingNews— POLITICO (@politico) April 17, 2013
UPDATE: All clear given in the Senate office buildings:
The U.S. Capitol Police have removed the suspicious package from Hart and the envelopes from Hart and Russell. The areas are now open.— Stew (@StewSays) April 17, 2013