Wildfires that have already forced thousands in the eastern Canadian province of Nova Scotia to evacuate continued to burn on Thursday, causing poor air quality hundreds of kilometres away as smoke drifted south across the United States border.

Federal help was coming, officials said, along with about 100 firefighters from the US, after local authorities appealed for outside assistance.

Canada’s federal government had already “provided airlifts, aerial surveillance, crew comfort trailers, and food at the emergency shelters”, Sean Fraser, a cabinet minister and parliament member from Nova Scotia, said on Twitter on Thursday.

The formal request for help will allow the government to provide additional resources, he said.

“We’re in a crisis in the province and we want and we need and we will take all the support we can get,” Nova Scotia Premier Tim Houston told a news conference on Wednesday, asking for assistance.

“Unprecedented resources are being used because these fires are unprecedented.”

Already, additional kits have been shipped in from Ontario, and a dozen water bombers from neighbouring regions and the Coast Guard joined efforts to douse the flames and assist with evacuations.

Houston said he has also asked for the military to help out.

Prime Minister Justin Trudeau called the wildfires “heartbreaking” and promised unlimited support.

As of late Wednesday, 14 wildfires were burning in Nova Scotia, including three out of control. They have so far destroyed or damaged more than 200 homes and other structures, including a wooden bridge, but no injuries have been reported.

Smoke from the wildfires blew down the Atlantic coast, prompting air quality alerts for the US state of New Jersey and parts of Pennsylvania, including the Philadelphia area.

David Meldrum of the Halifax Regional Fire and Emergency, pointing to record-high temperatures forecast this week, warned of “a prolonged operation” to bring under control a large fire northwest of the port city that has displaced more than 16,000 residents.

Hot dry weather was forecast Thursday, with rain predicted for late Friday.

“People are understandably tired, frustrated and frightened,” said Halifax Mayor Mike Savage, adding that “some have no home to return to”.

Houston announced a ban on all activities in Nova Scotia forests, including hiking, camping, fishing, hunting, the use of off-road vehicles and logging, and on Wednesday increased the fine for violating the burn ban to about $18,000 (25,000 Canadian dollars).

Government data shows a decline in the number of wildfires in Canada since the 1980s, likely due to improved fire prevention.

But the past decade also saw more disastrous wildfires scorching a lot more land and displacing many more people – problems set to worsen with climate change.

In recent years, western Canada has been hit repeatedly by extreme weather, including floods and mudslides, forest fires that destroyed an entire town, and record-high summer temperatures that killed more than 500 people in 2021.

On Tuesday, 800 residents of Fort Chiepwyan in northern Alberta had to be airlifted to safety as fires bore down on the remote hamlet.

Earlier this month, wildfires in Alberta burned nearly one million hectares (2.74 million acres) of forests and grasslands, and at one point, displaced 30,000 people.