Update - Building evacuated in Civic

An estimated 50 people have been evacuated from the ground and first floors of the office building.

Firefighters have identified a small gas leak in a plant room which is believed to have spread into a number of air-conditioning vents on the first two floors of the building.

There are no reports of injuries at this stage.

ACT Fire & Rescue is on scene with two fire pumpers, a Commander and the HAZMAT Unit.