A white powder found in an envelope at the Lincoln Plaza Building in Downtown Dallas Tuesday morning turned out to be hazardous.
Dallas Fire-Rescue was called to 500 N. Akard at about 11:19 a.m. after an employee in a mailroom on the 40th floor opened an envelope and white powder spilled out.
The employee notified a supervisor, who also became exposed, and 911 was called.
DFR's Hazmat team arrived and determined the letter inside the envelope was non-threatening, but that the powder was indeed hazardous. The exact substance was not determined, however, and a sample was sent for further analysis.
Officials released no other details about the letter.
The two mailroom employees showed no signs of hazardous exposure and were not hospitalized.
The investigation has been turned over to the Dallas bureau of the Federal Bureau of Investigation.
Letters containing powder invoke fear after five people were killed and more than a dozen were injured when letters laced with anthrax spores were mailed to offices in the days and weeks after Sept. 11, 2001.
Since then, hundreds of hoax letters have been received nationwide at schools, banks, hospitals and other businesses. Though the vast majority of white powder letters have been harmless, anyone receiving a white powder letter is advised to evacuate the area and call 911.