Update (7:40 p.m.) Cheyenne Fire and Rescue spokesman Mark Norford says the building was cleared Monday evening and the substance was not hazardous. 

Emergency responders were called to the federal building this afternoon on a report of a suspicious envelope containing a bag containing white powder, that's according to Cheyenne Fire and Rescue spokesman Mark Norford

Norford says occupants of the building were sheltered in place until the building could be cleared.