Capitol Police have given the clear sign on three suspicious packages found at Senate Office Buildings on Wednesday.
Two of the packages were in the Hart Senate Office Building, and a third was in the Russell Senate Office Building.
A public address announcement in Hart said that all tests on the suspicious envelopes came back negative.
Senate sergeant at arms Terry Gainer told The Hill that the letters were reported as suspicious because they were hand-delivered and not screened by the mailing facility in Maryland beforehand.
Capitol Police issued messages to the Senate offices that they were responding to suspicious envelopes on the third floors of both buildings and the atrium of the Hart building.
The message directed staff and other personnel to avoid those areas until further notice.
Capitol Police ordered staffers in the buildings to remain in their offices and ordered people out of the hallways.
Another suspicious package was reported on Wednesday in Saginaw, Mich., at Sen. Carl Levin’s (D-Mich.) district office.
The suspicious package reports come as security on Capitol Hill is being tightened following the Boston Marathon bombings and the disclosure of a letter to Sen. Roger Wicker (R-Miss.) that included the deadly poison ricin.
A second letter containing ricin was sent to President Obama, according to the FBI.
Gainer, told Senate offices in an email that mail would not be delivered on Thursday or Friday as a result of the ricin attack. He expected the normal mail delivery would resume on Monday.
Wednesday's mail would be delivered to D.C. offices, Gainer said, because it had already been inspected before the ricin letter was received.
Updated at 2:10 p.m.