Canadian Prime Minister Justin Trudeau paid tribute Friday to crews who fought to save fire-ravaged Fort McMurray, amid criticism for not showing up in the city sooner.

"The work that you did to save so much of this community, to save so much of this city and the downtown core and so many homes was unbelievable," Trudeau said from Fort McMurray, after flying over areas that had been devastated by the fires.

The entire city of 100,000 people was evacuated last week. Its suburbs suffered major damage, but the city center was largely spared.

As of Friday, only one fire remained out of control, about 40 kilometers (25 miles) east of the city.

Canadians were only "beginning to hear the wonderful news that so much of the town was saved," Trudeau told a group of rescuers in Fort McMurray.

He also toured part of the Beacon Hill neighborhood, which fared far less well, and is in ruins.

Accompanied by Alberta Premier Rachel Notley, Trudeau was to appear later in the day in the province's capital, Edmonton, where a number of evacuees have taken refuge.

Trudeau was welcomed to Fort McMurray by firefighter chief Darby Allen before surveying the damage from an army helicopter.

The prime minister expressed interest in preventing a disaster of the same magnitude from happening again.

"I'm very, very interested in not just what we manage to do to get through this one but what we can do around minimizing the impacts of the next one because it will come," Trudeau said.

Fires are not uncommon in the region at winter's end, but are generally not as destructive as the McMurray blaze, which burned 2,415 square kilometers (1,500 square miles), according to fire services in the province.

Trudeau also responded to criticism that he had not come sooner to the city.

"I was not able to get here until now, so I was following all of the updates and watching the images on TV and seeing the scale of this" Trudeau said.