ROSWELL, Ga.  – Authorities are investigating suspicious packages mailed to a congressional candidate, her neighbors and Atlanta news stations.

Several media outlets report the letters had a Greenville, SC postmark.

The FBI says the letters contained a powdery substance and were sent to Republican congressional candidate Karen Handel and her neighbors.

A package containing a threatening letter and powder was also sent to FOX 5 Atlanta. The news station reports that tests revealed the substance was baking soda. The station is also reporting the package contained a threatening letter.

11 Alive, another news station in Atlanta, reported that a suspicious package was also received there and that the powdery substance was baking soda.

The FBI says initial field testing for all of the letters indicated negative for any known hazards.

Karen Handel said in a Facebook post that suspicious packages were delivered to her house, as well as her neighbors.

One of Handel’s neighbors provided a copy of the letter to the Atlanta Journal Constitution. The newspaper reports the letter read “your neighbor Karen Handel is a dirty fascist” expletive and told the recipient to take a “whiff of the powder and join her in the hospital.”