The FBI is trying to find out who sent a handful of letters containing a suspicious powder, to various Congressional offices.
The letters were postmarked from Portland. Local FBI spokeswoman Beth Anne Steele says while the powder has been tested and is not anthrax, sending a threat is still a serious crime.
"Although the vast majority of white powder letters are determined to be hoaxes, no threat is taken lightly. We are investigating and we are treating each incident as a potential real event, and we're working with our local, state and federal partners to investigate these matters."
Steele says the FBI has had scattered reports of letters, so there's no full accounting at this point.
The Senate's top law enforcement officer says letters were sent to three state and home district offices, and that the author threatened additional letters that could contain harmful material.