A report of an unusual smell saw firefighters called out to Yellowknife's Crestview Manor apartment building on Monday evening.
Emergency responders on the scene said a "substance smell" was being investigated.
Few if any of the building's residents appeared to have been evacuated.
Fire crews briefly ventilated an area of the 52 Avenue building. There were no injuries reported.
Surrounding roads were closed by municipal enforcement officers while crews examined the building.
It's not clear what the substance may have been. Recently, there have been reports of bear spray discharged at buildings on Sissons Court and Gitzel Street.
Crestview Manor was the scene of a small fire that gutted one of the building's apartments earlier this month.
A fire truck outside Yellowknife's Crestview Manor on September 30, 2019. Andrew Goodwin/Cabin Radio
Sarah Pruys and Andrew Goodwin contributed reporting.