Residents of Yellowknife's Norseman Manor apartments were evacuated on Wednesday evening as fire crews were called to the building.
Firefighters arrived at the 52 Avenue complex just after 9pm as residents waited nearby in the rain.
On Thursday morning, the City of Yellowknife said a small fire had been discovered in a storage unit on the first floor of the building.
"An attack team entered the structure, located the fire in a storage unit and extinguished it," read a City statement.
"A ventilation fan was set up to remove the smoke from the building. The fire was extinguished shortly after arrival on scene."
A total of 14 personnel attended the scene, while RCMP closed adjacent roads as crews investigated. No injuries were reported.
Norseman Manor is known locally for the frequency with which false alarms take place at the building.