GEOFF BENNETT: Good evening, and welcome to the "NewsHour."

The impact of wildfires is being felt on two fronts tonight.

On Maui, residents are trying to rebuild their lives days after fire scorched parts of the island as they are mourn the many lives lost.

But for one city in Canada's Northwest Territories, the fire danger is only just beginning.

Traffic lined the only highway out of Yellowknife today, while other residents packed airports amid urgent orders to evacuate.

TEBBIA TEONCEY, Yellowknife Resident: I have never seen anything like it.

And I have never heard anyone speculate that, in my lifetime, something like this would happen.

GEOFF BENNETT: It's a race against time.

A wildfire rages just a few miles north of Yellowknife, the capital of Canada's Northwest Territories, and home to some 20,000 people.

Forecasters say strong winds could push the flames into the city by the weekend.

This year has been the worst wildfire season in Canada's history.

More than 51,000 square miles have burned so far.

That's far more than the country's average wildfire season, which typically scorches 9,000 square miles.

The wildfire danger also extends to British Columbia as a heat wave is bringing sweltering temperatures.

CLIFF CHAPMAN, Director of Wildfire Operations, British Columbia: This weather event has the potential to be the most challenging 24 to 48 hours of the summer from a fire perspective.

We are expecting significant growth and we are expecting our resources to be challenged.

GEOFF BENNETT: Meantime, on Maui, local authorities are facing scrutiny after last week's wildfire wiped away the entire town of Lahaina, seemingly without warning.

QUESTION: Do you regret not sounding the sirens?

HERMAN ANDAYA, Former Administrator, Maui Emergency Management Agency: I do not.

The sirens, as I mentioned earlier, is used primarily for tsunamis.

And that's the reason why.

GEOFF BENNETT: Maui's emergency services chief, who defended his decision to not sound outdoor alert sirens as the fire raged, resigned overnight, citing health reasons.

That is as relief efforts continue.

Those whose homes were spared are banding together to help in any way they can.

CORRINE NOBRIGA, Lahaina Resident: It's a touchy situation right now, because for us, as a community, of course, we're happy that we have our homes, but our heart aches, because that's our other neighbors and our families.

GEOFF BENNETT: The search for victims continues, with more than 1,000 people still missing as of this morning.

President Biden is scheduled to visit the island on Monday.