JEFFERSON COUNTY, Colo. (CBS4)– A wildfire burning in Jefferson County sent smoke across the foothills on Thursday afternoon.

“Watching it actually grow it was a fast ordeal,” said witness Alex Engebretson.

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The fire was estimated at 100 acres and was burning about two miles west of 32nd Avenue and McIntyre on South Table Mountain near the Coors brewery.

Copter4 flew over the fire burning near the Coors plant in Golden (credit: CBS)

A helicopter makes water drops on the fire burning in Golden (credit: CBS)

Copter4 flew over the fire as a helicopter made water drops.

Crews were seen spraying the flames burning in the dry grass and shrubbery.

(credit: CBS)

Firefighters will fight the blaze from the top but the terrain on the slope of the mountain is too rugged for crews.

“A lot of dead fuel in here, just really hasn’t been safe to send any crews into this fire from this side,” said Fairmount Fire Department Capt. Damian Difeo.

Firefighters will let that portion burn through the night.

(credit: CBS)

CBS4 Meteorologist Chris Spears was in the Mobile Weather Lab tracking the fire danger along the Front Range.

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“It’s really varied, the wind would circle, so we would get a straight climb up the hill or we’d get an easterly climb… It just depended on the wind,” said Engebretson.

(credit: CBS)

“We’re going to patrol the road here on 32nd, try and hold the fire to the south side of 32nd and not let it spot across onto the Coors property,” said Difeo.

What caused the fire is being investigated.

(credit: CBS)

“I can’t remember the last time it was this dry in march that we’ve seen this many grass fires in the past few days,” said Difeo.

(credit: CBS)

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– See images from the most destructive wildfires (Black Forest, Waldo Canyon, High Park and Fourmile), the deadliest (Storm King) and largest wildfire (Hayman) in Colorado history.