Ingram Micro shut down a Millington, Tenn., warehouse Monday after an employee found a "suspicious" package that contained an unknown powdery substance.
It could be days before the substance is identified, but initial indications were that the package did not contain anthrax, according to an Ingram Micro spokeswoman.
About 400 employees of the distributor were evacuated from the distribution center, according to the spokeswoman.
The warehouse was shut down for six hours, from about 2 p.m. to 8 p.m., according to the spokeswoman.
Investigators from the FBI and FEMA arrived at the warehouse, removed the package, brought it to a laboratory for further investigation and cleaned up the site, said the spokeswoman.
Ingram Micro exercised all precautions to ensure its employees' safety, said the spokeswoman.