TORONTO (Reuters) - A fairly controlled fire grew to a 10,000-hectare inferno over the course of a day, causing 9,600 residents of an eastern Canadian community to flee and putting a nearby community on evacuation alert.

The fire northwest of Labrador City, in western Newfoundland and Labrador, was "deemed fully under control" as recently as Tuesday, Premier Andrew Furey told reporters Saturday. Perfect fire conditions on Friday changed that.

The fire grew from 600 hectares to 10,000, moving 21 kilometres in four hours, he said.

It became "an extremely aggressive inferno," he said, that forced the evacuation of Labrador City. The fire was about six kilometres from town Saturday midday. Nearby Wabush was on evacuation alert Saturday.

Waterbombers were attacking the fire and the province had requested assistance from other provinces and the federal government.

Thousands of people made the hours-long trek to Happy Valley-Goose Bay, about 500 kilometres away.

"It was untenable to keep people in Labrador City," Furey said, adding they had also evacuated a local hospital.

"We're very grateful to everyone who has packed up their belongings, packed up their families, packed up their pets and moved suddenly. So, thank you for being patient."

2023 was Canada's worst-ever wildfire season, when 18.5 million hectares burned and blazes raged simultaneously in the east and west of the country.

(Reporting by Anna Mehler Paperny; Editing by Nick Zieminski)