WASHINGTON - Three members of the US Congress have received threatening mail containing a suspicious powder later found to be harmless and law enforcement officials on Wednesday warned that more may be coming.
Another US law enforcement official said letters sent to television personalities Jon Stewart and Stephen Colbert threatened biological attacks on US senators.
Other letters to a number of news organizations and postmarked Oregon warned that 100 letters had been sent to the Washington or home-state offices of US senators and that 10 of those contained a deadly pathogen, a law enforcement source said.
At least two of the letters already received - one to the home-state office of a senator and the other to the district office of a member of the House of Representatives - contained a powdery substance.
Tests found the substance to be harmless, according to a statement by Senate Sergeant at Arms Terrance Gainer, the chamber's chief law enforcement officer.