Workers have been evacuated as precaution while HAZMAT crews conduct a sweep of the nine storey building.
A smell of gas was reported on four levels.
ACT Fire & Rescue have three pumpers, the Hazardous Materials Unit, Breathing Apparatus Van, Bronto Skylift Hydraulic Platform and a commander on site.
The ACT Ambulance Service are on scene but have not treated any patients.
Update to follow.