Tonto National Forest officials said a wildfire is burning in heavy brush in the Cave Creek area.
As of 10 p.m. Wednesday, the Rio Fire had burned 21 acres east of the Verde River.
Two helicopters, one air attack plane and four engines began their assault on the blaze, which ignited around 5:20 p.m. near the Needle Rock Recreation Area by the Verde River.
Forest officials said they grounded the aircraft at dusk, and they will be ready to launch again Thursday morning at 7 p.m. to reassess the fire's activity and their needs.
Forest officials said several engines will remain on the ground overnight to keep an eye on the situation.
No homes or other structures are threatened.
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