Chief Fire Officer Graeme Ferguson said two appliances were sent to the Clutha District Council main building about 3.55pm yesterday.
After inspection, it was determined the alarm was triggered in error and there was no need for concern.
The entire building was evacuated promptly once the alarm went off.
Mr Ferguson said the quick response from the council was an improvement on a previous experience when there was a chemical leak.
"Everything worked out well this time,'' he said.
"Things did not go quite according to plan [last time].''
In February, six council staff were rushed to hospital amid fears they may been poisoned by chemical fumes.
Other council staff went to hospital later in the day with similar symptoms.
Council chief executive Steve Hill confirmed the building was evacuated promptly yesterday as staff did not want to repeat past mistakes.
Once staff were told there was no risk, they were allowed to return to the building.
"Now we want to let the experts tell us if it's not a big risk,'' he said.
Mr Hill believed maintenance work carried out in the building yesterday might have triggered the alarm.
