Federal officials are investigating as an "anthrax hoax case" a white powdery substance sent to the political action committee office of former Vice President Al Gore Tuesday, an FBI official told Fox News.

"No one has been transported because of medical reasons, and no suspects have been identified," said Jon Stephens, spokesman for the FBI in Nashville.

A hazardous materials team was on the scene at Gore's "Leadership '02" PAC in Nashville after office manager Mary Patterson opened an envelope with the morning mail that contained the substance.

Gore is on vacation in California and in touch with staffers at the office.

Gore aides said that around 12:15 CDT, Patterson was opening the mail when she came across the questionable letter. When the powder fell from the envelope, aides said, Patterson called Nashville Director Robert McLarty, who told her to leave the area and wash down. They closed down the air conditioning unit, called the hazmat team and evacuated the office.

Aides said the letter was postmarked in Tennessee and had an additional stamp that raised Patterson's interest.

The additional stamp said: "This letter has not been inspected by the Corrections Department."

Steve Hayes, Tennessee Department of Correction spokesman, said it is policy to stamp letters that haven't been inspected as being sent from a correctional facility but the wording the department uses is different from what Jano Cabrera, a spokesman for Gore's D.C. office, described as being on the letter.

Test results are expected in the next couple of days, but Nashville Fire Department Assistant Chief Kim Lawson said the office will be closed for the next 96 hours as a precaution. She added that this is not the first phony anthrax case in Tennessee.

"This call is not a lot different than any other," said Lawson, whose department has responded to about 400 such incidents since Sept. 11. "It's a high profile office. That's what makes this different."

None of the Gore staff has been hospitalized but were quarantined on the scene.

Gore's PAC is located on the 7th floor of the Loews Hotel across from Vanderbilt University.

Fox News' Carl Cameron and the Associated Press contributed to this report.