Canada's wildfires, which have already forced evacuations of more than 26,000 people, continued their stubborn spread Tuesday, with heavy smoke choking millions of Canadians and Americans and reaching as far away as Europe.

Alerts were issued for parts of Canada and the neighboring United States warning of hazardous air quality.

A water tanker air base was consumed by flames in Saskatchewan province, oil production has been disrupted in Alberta, and officials warned of worse to come with more communities threatened each day.

"We have some challenging days ahead of us," Saskatchewan Premier Scott Moe told a news conference, adding that the number of evacuees could rise quickly.

Every summer, Canada grapples with forest fires, but an early start to the wildfire season this year and the s

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