CALGARY -- Crews are working around the clock to restore power and natural gas to the fire-ravaged city of Fort McMurray, but the chief operating officer of the utility that serves the area says it's impossible to say how soon residents will be able to go home.

It's slow and dangerous work.

"If you can imagine a charred power line pole that we don't want to take out of service, but we want to reinforce -- it's something we obviously want to do with great care," Atco COO Siegfried Kiefer said Wednesday following the company's annual meeting.

"Both of the products we deal with are invisible and both can kill you."

More than 80,000 people were forced to flee when a ravenous wildfire attacked several neighbourhoods in the northern Alberta city last week.

The blaze destroyed about 2,400 structures, but about 90 per cent of the city was saved.

Kiefer said about 75 per cent of Fort McMurray's buildings could have their power turned back on, but at this early stage it wouldn't be safe.

"We won't turn power on to many of the regions until inspections are complete," he said.

"Obviously you don't want to if there's any residual gas or if there's any kind of explosion potential."

As for natural gas, Atco cut off the supply to the city when the fire started as a safety precaution, Kiefer said, and turning it back on can't occur until gas lines are checked.

Alberta Premier Rachel Notley didn't have an update Wednesday on when Fort McMurray residents may be able to go back. Earlier in the week, after touring the city by ground, she said a schedule would be out in about two weeks.

"I understand it's hard for people not to have a definitive timeline," she said. "But at the same time, I don't want to give them a definitive timeline, have them build their hopes around that ... and then discover an infrastructure deficit that we didn't previously know about that delays things by a week or two."

Kiefer said he couldn't pinpoint how soon repairs will be completed, but suggested it would be "less than a month."

Once they are, re-entry is likely to be staggered, he said.

"That's how it worked in the Slave Lake fires. We took blocks of communities and allowed members of that area of the town to come in."

Atco also has a division that provides modular buildings, office trailers, workforce housing and camp and lodging services.

Kiefer said once first responders are done their work, the company will be making the most of 4,000 beds it already has available in the Fort McMurray area.

Atco is also willing to "ramp up" delivery of additional temporary housing if the province decides it's necessary for people returning to the city while their houses are rebuilt.

The mayor and councillors from the Regional Municipality of Wood Buffalo, which includes Fort McMurray, held their first meeting since the fire at Edmonton city hall on Wednesday.

They talked about the city's capital budget, about starting to plan for the eventual return of the evacuees, and the need for temporary housing as the city rebuilds.

"We're going to have a component that has inclusion of members of the province, explaining to myself and council what our roles and responsibilities are," said Mayor Melissa Blake.

"We're very anxious to get back into it. But at some point, we move from the phase that we're in to where we actually do end up taking over the recovery of our community."