Searchers originally feared that Falcon Heene, 6, might have been aboard the homemade balloon when it drifted away from his family's home. (KMGH-TV/Associated Press)

A six-year-old Colorado boy who was originally thought to have been on board a homemade helium balloon that was accidentally released and sailed through the sky for two hours has been found alive at his home.

Falcon Heene had been hiding in a box in the attic of the garage.

"How did it feel to see my son again? This is a relief. We have to watch him a lot closer," Falcon's father, Richard Heene, told reporters after the ordeal, choking back tears.

Heene said the family was tinkering with the silvery balloon in the backyard of his family's Fort Collins, Colo., home Thursday and he had yelled at Falcon for entering a compartment on the craft.

He said Falcon's brother saw him in the compartment and that's why they thought he was aboard the balloon when it left the ground.

"Brad said he saw it. He videotaped it and, sure enough, he [Falcon] got in and obviously he got out, so we don't know."

Six-year-old Falcon Heene sits in the box of his family's pickup truck outside their home after he was found hiding in a garage. (David Zalubowski/Associated Press)The balloon, owned by the family, covered about 80 kilometres and passed through parts of two counties during the two hours it was aloft.

Officials didn't know whether the boy was aboard when the craft floated away or whether he fell out during the two-hour flight.

"The only thing I could think of was that he had fallen out," Richard Heene said. "So I had to retrack back in my mind. Did he fall out?"

The balloon eventually deflated and came down in an empty field. Rescuers grabbed the craft and pinned it to the ground, only to find no sign of the missing boy.

Falcon had fled to the garage before the balloon had launched. He climbed a pole into the rafters and hid in a cardboard box at some point after being scolded.

"I'm really sorry I yelled at him," a tearful Heene said.

"I was in the attic and he scared me because he yelled at me," the boy said. "That's why I went in the attic."

His father said the balloon wasn't tethered properly and "it was a mishap. I'm not going to lay blame on anybody."

The boys' parents call themselves storm chasers. They also appeared twice in the ABC reality show Wife Swap, most recently in March.

Heene adamantly denied the notion that the whole thing was a publicity stunt. "That's horrible after the crap we just went through. No."

During an interview with CNN, Falcon said he had heard his family calling his name.

"You did?" Mayumi Heene said.

"Why didn't you come out?" Richard Heene said.

Falcon answered, "You had said that we did this for a show." Later, Richard Heene bristled when the family was asked to clarify and said he didn't know what his son meant. He didn't ask his son what he meant by "a show."

With files from The Associated Press