BANGOR – Postal employees at the Margaret Chase Smith Federal Building discovered an unknown substance Thursday afternoon, prompting an investigation by authorities who took a sample for evaluation.

Assistant Fire Chief Scott Bostock said the substance was described as being “crystallized” and was found in an isolated area, inside one of the sorting bins. A special hazardous materials team from Orono was brought in to investigate. A sample was being taken to a laboratory to determine what it was. The remainder of the substance was secured by the hazardous materials team.

The post office remained open.

Police and firefighters were called in about 3:55 p.m. and Bostock said firefighters left the scene at 5:45 p.m.