New York, Jun 7 (IANS): Smoke from Canada's wildfires has engulfed a wide swath of the northern US, triggering air alerts from Minnesota to Massachusetts.

In Ontario, a layer of haze blanketed parts of Ottawa and Toronto, where Canadian officials warned residents about the poor air quality, as smoke floated over portions of New York State and Vermont. All of New York City was under an air quality alert on Tuesday because of the smoke; by the afternoon, the Manhattan skyline was obscured by hazy skies, The New York Times reported.

More than 400 active wildfires were burning in Canada on Tuesday, according to the Canadian Interagency Forest Fire Centre, exacerbating an already active wildfire season that is only expected to worsen. More than 200 of the fires were burning out of control, the agency said.

In eastern Canada, Quebec was most affected by wildfires as of early Tuesday afternoon, with more than 150 active blazes across the area, according to the fire agency. Residents in some areas were being encouraged to shut their windows and doors, local officials in Quebec were quoted by NYT as saying.