'River Fire' burning south of Coolidge near Picacho Reservoir

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Dozens of firefighters were on the scene on Wednesday night of the River Fire in Pinal County. (Source: 3TV/CBS 5) Dozens of firefighters were on the scene on Wednesday night of the River Fire in Pinal County. (Source: 3TV/CBS 5)
Several "fire tornadoes" were spotted from the air Wednesday night. (Source: 3TV/CBS 5) Several "fire tornadoes" were spotted from the air Wednesday night. (Source: 3TV/CBS 5)
The agency said it should grow to a few hundred acres overnight because it's burning through salt cedar. (Source: AZ State Forestry/Twitter) The agency said it should grow to a few hundred acres overnight because it's burning through salt cedar. (Source: AZ State Forestry/Twitter)
No buildings are threatened. (Source: AZ State Forestry/Twitter) No buildings are threatened. (Source: AZ State Forestry/Twitter)
COOLIDGE, AZ (3TV/CBS 5) -

Crews are on the scene of a brush fire that is burning out of control in Pinal County on Wednesday.

When the fire was first reported, the Arizona Department of Forestry and Fire Management said the fire, now named the River Fire, had scorched about 30 acres near the Picacho Reservoir, which is 11 miles south of Coolidge.

At around 7 p.m., there were around 80 firefighters at the fire.

The agency said it should grow to a few hundred acres overnight because it's burning through salt cedar.

[RAW VIDEO: Aerials of River Fire south of Coolidge]

On Thursday morning, the fire increased 10 acres, to a total of 40 acres burned. However, the department said once daylight comes, they will have a better mapping of the fire and exact acreage.

[RAW VIDEO: ‘Fire whirls’ spotted at wildfire south of Phoenix]

No buildings are threatened.

However, some of the smoke could impact Coolidge.

It's unclear what caused the fire.

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