The strange package with white powder was reported inside Dallas Mayor Pro Tem Dwaine Caraway's office on the 5th floor.
Sources very close to the investigation said initial tests by HazMat crews on scene revealed the white powder sent to Caraway was cocaine.
Police confiscated the drugs to send to the lab for further testing.
There was a note included in the package as well as a return address listed on the envelope. Detectives are already on the way to the address listed on the package.
During the investigation police restricted all access to the 5th floor and quarantined everyone inside the council member's administrative offices. No evacuations were ordered.
The city council was in its last session before the council members went on summer break.