The FBI has taken action to prevent threatening letters containing white powder from being mailed in Portland. The FBI's Beth Anne Steele wasn't able to say what they did to stop the letters. Steele says that's it's possible that letters still in process could be delivered. She says no arrests have been made and no one is in custody. Six letters have been received at various offices around Portland. None of them contained toxic material. The state health lab is trying to determine the content of the powder.