The youngster is still missing and there are concerns he may have fallen from the craft, although there was no confirmation this had happened.
A spokesman for the Colorado National Guard told Sky News the boy's brother had said he saw him fall out of the balloon but that report "is unsubstantiated".
Eloise Campanella of Larimer County Sheriff's Department told CNN: "The bottom of (the balloon) is contained and hasn't been breached.
"So at this point we are thinking he did not fall out of it. He has to be somewhere on the ground near his home."
Falcon's father Richard Heene built the balloon at his family's home in Fort Collins, reportedly as part of his work as an amateur scientist.
Heene, who once appeared on TV as the father of a "storm-chasing, science-obsessed" family, said the craft was hovering above the ground before it came loose.
Captain Michael Hodges, from the Colorado National Guard, told Sky News: "I don't know if that's good news or not, that the boy is not in it.
"We are now going to begin trying to find out where that child is."
Breaking News
10:38pm UK, Thursday October 15, 2009
Boy Still Missing In Hot Air Balloon Drama
US police are searching for a six-year-old boy after the homemade helium balloon he was thought to be inside came down to earth empty.
The silver, flying saucer shaped object, which is about 20ft across, had drifted off after coming loose from its moorings - apparently with Falcon Heene inside.
The boy's brother said he saw the six-year-old climbing into the contraption before it became untethered.
The runaway balloon soared up to 7,000ft in the air and reached speeds of 25mph.
It drifted for miles across the Colorado skies before landing gently in the desert after slowly deflating.
Rescue workers, who grabbed the object as it floated down to the ground, opened it and failed to find Falcon.
Richard Heene, wife Mayumi and three children Bradford, Ryo and Falcon
Falcon Heene is the youngest child (Picture: ABC)
The youngster is still missing and there are concerns he may have fallen from the craft, although there was no confirmation this had happened.
A spokesman for the Colorado National Guard told Sky News the boy's brother had said he saw him fall out of the balloon but that report "is unsubstantiated".
Eloise Campanella of Larimer County Sheriff's Department told CNN: "The bottom of (the balloon) is contained and hasn't been breached.
"So at this point we are thinking he did not fall out of it. He has to be somewhere on the ground near his home."
Falcon's father Richard Heene built the balloon at his family's home in Fort Collins, reportedly as part of his work as an amateur scientist.
Heene, who once appeared on TV as the father of a "storm-chasing, science-obsessed" family, said the craft was hovering above the ground before it came loose.
Captain Michael Hodges, from the Colorado National Guard, told Sky News: "I don't know if that's good news or not, that the boy is not in it.
"We are now going to begin trying to find out where that child is."
He said the area they now had to search was "quite extensive" and added: "Hopefully we can take care of that as quickly as possible and hopefully bring this to a happy conclusion."
Sky's US correspondent Robert Nisbet said: "The balloon was in the air for two hours and travelled a distance of 60 miles.
"You can imagine how difficult such an extensive search would be."
http://news.sky.com/skynews/Home/World-New...aft_In_Colorado