More threatening letters containing a suspicious powder were sent to Capitol Hill.
Senate Sergeant-at-Arms Terry Gainer said the Senate's off-site mail facility intercepted the letters Monday morning.
“In addition to the suspicious letters sent to Senate state offices last week, similar letters addressed to Senate offices in D.C. have been received,” Gainer wrote in an email to lawmakers, the Hill reported.
Initial tests indicate the powder was not hazardous. There was no immediate word on how many lawmakers were targeted, or which ones.
Similar letters were sent to Senator's home offices last week. All of them had a harmless, powdery substance inside.
The letters have all been postmarked from Portland, Oregon.
In one of the letters obtained by the Associated Press, the sender seeks "an end to corporate money and 'lobbying'" and denounces "corporate personhood."