An envelope containing ricin was sent to the Capitol Hill office of Sen. Roger Wicker, lawmakers told Fox News on Tuesday.
The letter to the Mississippi Republican was intercepted at an off-site mail screening facility, and never made its way to the Hill.
“It is of concern,” Sen. Angus King, I-Maine, said, after learning about the incident in a briefing with other senators late Tuesday.
Fox News has learned that the envelope tested positive for ricin.
Read more: nation.foxnews.com