The balloon landed south of Prospect Springs, near Colorado Springs.
The boy was not inside the helium aircraft when it landed, KMGH reported.
A sibling saw the boy get into the craft Thursday morning. Officials were concerned that the boy may have fallen out of it, an undersheriff said.
Margie Martinez of the Weld County Sheriff's Office said a sibling saw Falcon Heene climb into the basket before the balloon took off from his parents' home.
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