Threatening letters that claim to contain dangerous pathogens believed to have been mailed from Oregon were sent to U.S. lawmakers and media companies across the country, law enforcement officials said Wednesday.
The person sent letters to Jon Stewart of "The Daily Show" and Stephen Colbert of "The Colbert Report," claiming more letters had been sent to 100 senators and various media companies, including The New York Times, Fox News and NPR law enforcement officials said.
But a federal law enforcement official, speaking on condition of anonymity, told the Associated Press that fewer than 10 members of Congress had received letters.
A GOP aide told NBC News that one of House Speaker John Boehner's district offices received mail Tuesday containing a powdery substance that proved to be harmless.
Kirotv.com, a Seattle station, reported that Sen. Patty Murray's office confirmed receiving a letter at the senator's office on the 29th floor of Seattle's downtown federal building.
KITV.com in Honolulu reported that a letter with suspicious substance was received at the federal building there. Fire crews used field equipment to test the letter for contaminants and found it wasn't toxic. They gave the letter to the FBI for more testing.
The letters, which were postmarked from Portland, Ore., contain threats claiming that 10 percent of the envelopes had dangerous pathogens. Officials said the writer voices anger over corporate greed and the state of the U.S. economy. The letters are signed "MAB."
The address given — 2413 NW Burnside, ZIP code 97209 — does not exist.
At least two of the letters contained a suspicious powdery substance, authorities said. 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.
Officials stressed that so far there is no evidence a dangerous substance has been sent. They point out there have been numerous hoax mailings in the years since the 2001 anthrax attacks.
Gainer said offices should be on alert because "the author of the letters has indicated that additional letters containing a powdery substance will be arriving at more Senate offices and that some of these letters may contain an actual harmful material."
Senate staff are being warned to look out for letters postmarked Portland, Ore.
New York authorities, meanwhile, are reaching out to security officials at major media companies.
The FBI in Oregon has been contacted to try to help track whoever sent the threatening mail.
This article includes reporting by NBC News and Reuters.
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