White Powder Letters Shut Down Marketing Firm in Dallas - kcentv.com - KCEN HD - Waco, Temple, and Killeen

(KCEN) -- Two letters containing white powder shut down a marketing firm in Dallas. 

Two employees at Allied Marketing were exposed to the powder, but showed no symptoms of being exposed to anything toxic.

Plano's Hazardous Materials team tested the powder, which came back negative for a hazardous substance.

The case is being turned over to the FBI's Dallas office.

Five people were killed and more than a dozen were injured when letters laced with anthrax were mailed to offices in the days and weeks after September 11, 2001.