The two-alarm fire broke out at 1:50 p.m. in the building's basement on Thursday but little damage was done to the building and the fire was quickly brought under control.
CBC's Linda Ward was outside the building Friday and at 6:30 a.m. reported that crews were still working to get the lights back on.
"It's pitch black here right now outside city hall and there is not a single light on," she reported.
Ward said two generators, each the size of tractor-trailers, are operating behind the building.
Staff and others who work at City Hall are advised to report for work as usual on Friday and to stay in touch with their supervisor or manager for updates and further direction. The Hester How Daycare in the building will be closed and parents are asked to make other arrangements for their children.