'Diamond' wildfire continues to burn in outskirts of Phoenix as residents return following evacuations

The Diamond Fire quickly grew to 2,500 acres, prompting evacuations in North Scottsdale and Southwest Rio Verde. The fire is just outside Tonto National Forest.

SCOTTSDALE, Ariz. A fast-growing brush fire temporally prompted evacuations in the outskirts of Scottsdale, Arizona, as fire crews worked to contain the blaze.

The Diamond Fire quickly grew to 2,500 acres, prompting evacuations in North Scottsdale and Southwest Rio Verde. The fire is just outside Tonto National Forest.

As of late Wednesday evening, the fire decreased to 1,960 acres and was 30% contained but still poses a threat. 

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The Diamond Fire in Scottsdale, Arizona. (Image: Arizona State Forestry) (@azstateforestry / Twitter)

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The Diamond Fire in Scottsdale, Arizona. (Image: Arizona State Forestry) (@azstateforestry / Twitter)

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The Diamond Fire in Scottsdale, Arizona. (Image: Arizona State Forestry) (@azstateforestry / Twitter)

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Smoke from the Diamond Fire in Scottsdale, Arizona. (Image: Arizona State Forestry) (@azstateforestry / Twitter)

The Arizona Department of Forestry and Fire Management said the fire was determined to be human-caused. Officials said they would not be releasing information on the ignition source at this time due to the ongoing investigation.

Multiple homes were impacted and immediately threatened, forcing the evacuation of 100-plus homes and 1,145 residents, authorities said. As of 7 p.m. Wednesday, all evacuations were lifted, and residents were able to return home. McDowell Mountain Regional Park still remains closed. Some trails within the Scottsdale trail system in the McDowells are also closed.

About 150 firefighters remain on the scene Thursday to battle the blaze.

Fire Weather Warnings were in place Tuesday when the fire started and have since been removed for the area. On Thursday, the only warnings remained in southwestern Colorado until 8 p.m. MDT for gusty winds, low relative humidity and dry fuels.