Letter sent to senator tested positive for ricin
The letter was postmarked from Memphis, Tennessee, and had no return address, Terrance Gaines, the Senate sergeant at arms, said in a warning to members of the Senate.
"Senate employees should be vigilant in their mail handling processes for ALL mailings," Gaines said in a written statement.
Members of the Senate were briefed on the ricin incident by Gaines during a meeting with FBI Director Robert Mueller and Janet Napolitano, the secretary of Homeland Security, on Tuesday on the bombings in Boston.
Several senators told reporters after the briefing that incident reminded them of the anthrax attacks in the wake of the September 11, 2001, attacks on the Pentagon and World Trade Center.
"I don't know if it's a coincidence. It's too early to tell. We don't know enough about Boston," said Senator Richard Durbin, the No. 2 Democrat in the Senate.
Several senators said that all mail to the U.S. Senate had been stopped and post offices at the Capitol had been closed as a precaution. They said they were getting in touch with their state offices, where mail is not routinely screened, to ensure that precautions were being put in place.
They said they were aware of only one letter that had been intercepted that tested positive for ricin.
It was not immediately clear whether Wicker had attended the briefing by Mueller and Napolitano, which was open to all senators from both parties.
A spokeswoman for the Mississippi senator referred inquiries to U.S. Capitol Police. A spokesman for the Capitol Police could not immediately be reached for comment.
Ricin is a lethal poison found naturally in castor beans.
(Additional reporting by Rachelle Younglai and David Lawder; Editing by Cynthia Osterman)..