Power should be restored by Thursday​ to thousands of downtown Calgary businesses and residents left in the dark on the weekend by an underground electrical fire.

The power outage hit approximately 2,100 businesses and 5,000 residents on Saturday night.

Late Monday afternoon, Alberta Premier Jim Prentice and Mayor Naheed Nenshi met with impacted downtown residents at an emergency information centre set up in the Mewata Armoury.

"I think it's fair to say that once again Calgary and Calgarians have risen to the challenge and are showing incredible resiliency and community spirit," Prentice said later in a press conference.

Power should be restored to the entire impacted section of the downtown by midday Thursday, said an Enmax official.

Transportation downtown should be almost back to normal for the Tuesday morning rush hour, Nenshi said during a news conference held early Monday at the Calgary Emergency Management Agency headquarters.

There will be some lane reductions, particularly on Eighth Street S.W., but traffic signals and C-Train service will be functioning.

"We are working on a traffic management plan for commuters entering into the downtown core," he said. "We believe there will be minimal disruptions. It will just be a miserable rush hour, as always."

Employers and employees need to check in with each other as it "will not be business as usual" in the impacted areas, Nenshi said.

Displaced residents staying in hotels

The Mewata Armoury's emergency information centre was busy on Sunday with 361 people showing up seeking assistance. About 270 people were helped with overnight accommodation.

"We hope that we have made things just a little bit easier for the people who were affected by the power outage," he said. "Once again, if you have friends and family with whom you can stay, that is the most comfortable thing to do."

The information centre will close at 10 p.m. Monday and reopen at 11 a.m. Tuesday.

Grace Eddy was at the armoury looking for help from the city because she only moved to Calgary two weeks ago.

"I don't know anyone and my family is in Ontario, so it was nice there was somewhere to come," she said. "It was scary coming here, but seeing that there was other people in the same situation made it a little bit more comforting."

Calgary courthouse closed

The damage from an underground fire in downtown Calgary on Saturday night was extensive, "completely destroying" the electrical infrastructure involved, the utility company Enmax said.

The cause of the fire is under investigation. About 3.5 kilometres of cable need to be replaced.

The outage has impacted several government buildings, including the Alberta government's McDougall Centre. That building is the premier's Calgary office and Prentice said he will be share an office with the Calgary mayor at city hall until power is restored.

The Calgary Courts Centre will be closed until Friday.

During that time, emergency applications will be dealt with by a Queen's Bench justice at the Court of Appeal, which is in the TransCanada Pipelines Tower.

The fire has affected some land-line 911 service.

Advice for downtown residents

Downtown residents who have not already left their homes should make a decision whether to stay or go before the sun sets, emptying the fridge before they go, Nenshi said.

"A number of people will be coming back to town after a weekend away to find that they don't have electricity or water. If that is the case, I strongly suggest you register at Mewata and continue to get updates by visiting Calgary.ca."

Despite the outage, the City of Calgary says water quality remains high and people affected by the outage can still use water — if it is available. The area of the outage contains many high-rise buildings and the lack of power may mean a loss of pressure and water supply to high-floor units.

City crews have emergency potable water wagons deployed in the affected downtown area for those without running water. There is also a food disposal bin available at the Mewata Armoury​.

Canada Post is suspending delivery until power is restored, but mail can be picked up at the facility at 1100 49 Avenue N.E. Mail normally picked up at the post offices on Fifth Avenue and Eighth Avenue will be available at the Calgary South postal outlet on 6100 Macleod Trail S.W.

Earlier, Nenshi urged people to exercise good judgment given that ventilation systems are without power.

In particular, he said, people should not run generators indoors or keep their car running in underground garages because they could get sick from carbon monoxide poisoning.

The city has been issuing updates on the situation on its Twitter feed @cityofcalgary.