U.S. Capitol Police are investigating suspicious packages in two Senate offices.

One package was delivered to the front office of Sen. Richard Shelby, an Alabama Republican, in the Russell building. Jonathan Graffeo, a spokesman for Shelby, said in an email that he had no further information.

At noon on Wednesday, Capitol police were also investigated a suspicious package left in the atrium of the Hart Senate Office building. First floor offices in the building were evacuated and people in higher floors were told stay in their offices.

According to CNN, a man with letters in his backpack is in custody at the Hart building and is being questioned. A Capitol Police aide confirmed that authorities are “talking with someone” but called reports that he has been arrested incorrect.

A letter addressed to President Obama containing a suspicious substance was intercepted Tuesday by authorities at a remote White House mail screening facility, according to the Secret Service. A ricin-laced letter was sent to Sen. Roger Wicker (R-Miss.) earlier Tuesday. Sen. Carl Levin (D-Mich.) also reported that a "suspicious-looking letter" was found at his Saginaw, Mich. office. Sen. Jeff Flake (R-Ariz.) likewise reported on a "suspicious package" at his Phoenix office that was found to contain no dangerous material.