GEOFF BENNETT: An especially active fire## season is exacting a huge toll# across several Western states.

A series of fires have turned deadly in# Colorado, where at least one person was## found dead.

In California, more than 5,800# personnel, 500 fire trucks and 40 helicopters## are battling a fire that's larger than all# of Los Angeles.

The Park Fire, as it's known,## is the country's largest and has ballooned# to historic proportions in just over a week.

Stephanie Sy has the latest.

STEPHANIE SY:## This is the view for firefighters on the front# lines of California's Park Fire.

The blaze,## believed to be started by a local man's burning# car, is now the fifth largest in state history.

SERGIO ARELLANO, Cal Fire: I have not personally## seen a fire grow so fast in# such a short.. STEPHANIE SY: In just a week, nearly# 400,000 acres burned across four counties,## forcing thousands of evacuations and# destroying hundreds of structures.

In rural Cohasset, California, Dave Tehan and his# son Jonathan are both members of the county fire## department.

While they battle to protect their# town, their own homes were lost to the flames.

DAVE TEHAN, Volunteer Firefighter: I feel# luckier than some of the people here,## because we do have a few things, not very much,## but a few things to hold in our hands that# survived.

The friends from -- that I have## known for so many years have just stepped up# and shown so much support.

I feel rich in that.

STEPHANIE SY: Kristy Michael Daneau also# live in Cohasset.

They lost their house## to another fast-moving fire six years ago# in Paradise, California.

Now this is all## that remains of the home where they rebuilt# their lives.

They had no fire insurance.

KRISTY DANEAU, Wildfire Evacuee: The# most important things I grabbed was## me and my brother and sister have my mom's ashes,## along with my dad.

And so I was able to# grab a few little pictures and her ashes.

STEPHANIE SY: The Park Fire's explosive# expansion is nearly unprecedented,## says UCLA climate scientist Daniel SWAIN.

DANIEL SWAIN, Climate Scientist, UCLA: This# is definitely a top-tier event in terms of## how quickly it moved across the landscape in those# initial days, some of the vastest rates of spread## over that initial 24-to-48 hour period that we# have seen on a wildfire in this part of the world.

STEPHANIE SY: Nearly 100 fires are# currently burning across the West## and 4.5 million acres have already burned# this year, about a million above average.

This week, multiple blazes broke# out across Colorado's Front Range,## killing at least one person and forcing# residents to flee their homes near Denver.## Governor Jared Polis has now activated the# National Guard to assist with logistics.

Meanwhile, in Oregon, crews are stretched# thin, battling more than 30 separate fires.

DON CAPE, Oregon Resident: I have lived here# all my life and never, never seen it this way.

STEPHANIE SY: To make matters worse,## another brutal heat wave is forecast to# turn up the temperature this weekend,## a dynamic that Swain says continues to drive# the intensity of this year's fire season.

DANIEL SWAIN: It has become a very active# season.

And a big part of the reason for this## is that nearly the entire western half of the# country as well, as the western half of Canada,## have experienced, much like California has,## record-breaking heat in recent weeks# over a very long and sustained period.

So all of that extra heat, even following what# was a relatively wet winter in some places,## has really dried out the vegetation, in# some cases to near-record dry levels.

STEPHANIE SY: And that means there's# plenty of fuel for the fires yet to burn.

For the PBS "News Hour," I'm Stephanie Sy.