There may be a possible Oklahoma connection to a suspicious envelope mailed to a journalist at the Saint Petersburg Times in Florida.
Inside there was a powdery substance and a letter that mentioned Oklahoma City.
The note specifically refers to the Oklahoma Ryder Truck - the truck used by Timothy McVeigh in the Oklahoma City bombing.
The letter also makes a vague comparison to another tragedy - when an ocean liner collided with the Saint Petersburg Skyway bridge.
Oklahoma City emergency officials say they are prepared to handle the threat of bio-terrorism.Dr Dave Hogan, OKC Emergency Physician:
"I and others have been working throughout this state to ensure that emergency physicians and paramedics are familiar with Anthrax as well as other forms of potential bio-terror."
Officials say the substance in the letter turned out to be harmless.
F.B.I. investigators say you should avoid opening anything missing a return address, and look for misspelled words or mail addressed only to your job title. The F.B.I. has an advisory with more information on mail safety, click here to get the advisory in printable Adobe Acrobat form.