Neighbours of 921 Bigelow Cres. called the fire department around 10:30 p.m. when they smelled smoke and heard a smoke detector, said deputy fire Chief Clem St. Croix.
The residents weren't home at the time and nobody was hurt.
The fire was caused by an incense-type of candle resting on a box that was left burning unattended, the deputy said.
Left burning for two to three hours, the candle burned down low enough for the box to catch fire.
There was minimal fire damage but considerable water damage when sprinklers in the building went off and dowsed the fire.
It took firefighters about 20 minutes to find and turn off the water valve, said St. Croix.
The Bigelow units are owned by Char Developments and are subleased by Yellowknife Housing Authority.