Authorities are investigating a ricin scare at US Logistics in Brownsville.
Brownsville police told Action 4 News they received a call about a suspicious package found inside the mailroom at U.S. Logistics located on the 200 block of Vermillion Road.
The employees have been evacuated.
All tractor trailers inside the gated facility are being allowed to leave, but no cargo is being allowed inside the area.
Brownsville police have the area heavily guarded.
Just before 2 p.m. Thursday, authorities determined the white powdery substance was not ricin.
More test will be ran to determine what is it.
US Logistics is federal mail distributor to the United States Embassy and Consulates' in Mexico.