(CNN) -- The 6-year-old Colorado boy who is believed to have set adrift a helium balloon Thursday, prompting ground and air searches, has been found alive, authorities said.
Falcon Heene was found in a box in the attic of his family's Fort Collins home, according to authorities.
People across the world watched Thursday as the homemade helium balloon soared 7,000 feet over eastern Colorado for more than an hour and a half.
A sibling said he saw the Falcon get into the craft Thursday morning, authorities said.
But the boy was not inside the craft when it made a soft landing near Keenesburg, about 60 miles from its starting point, at 1:35 p.m. (3:35 p.m. ET). See the balloon's path »
Shortly after the landing, authorities launched a ground search and suggested that Falcon never took off in the balloon.
"I'm very confident we will find him. I think it's a matter of him being a little scared," Larimer County Sheriff's Office spokeswoman Eloise Campanella said. "Maybe he's not ready to be found." Watch the balloon float thousands of feet over Colorado »
Falcon's parents, science enthusiasts Richard and Mayumi Heene, were featured on the 100th episode of ABC's prime-time program "Wife Swap" in March, ABC said.
According to the network's Web site, the Heene family devote its time "to scientific experiments that include looking for extraterrestrials and building a research-gathering flying saucer to send into the eye of the storm."
Richard Heene is a meteorologist and former television weatherman who has submitted to CNN iReports accounts of his sons helping him chase Hurricane Gustav, among other contributions.
The dome-shaped balloon, about 20 feet long and 5 feet high, appeared to be a Mylar-coated helium balloon, similar to a party balloon.
It had been tethered to the family home, the Larimer County Sheriff's Department said. The boy got into the craft Thursday morning and undid the rope anchoring it.
Before the balloon touched the ground, fears that the boy could be riding in the soaring vessel prompted the Colorado Air National Guard to launch a rescue mission Thursday afternoon to see if the agency could use a helicopter to steer the aircraft to safety, a spokesman said.
Officials could not immediately confirm how fast the balloon was going while airborne. Learn more about hot air balloons »
Marc Friedland, the family's next-door neighbor, said he saw Richard Heene working on the giant Mylar balloon in the backyard.
"Basically, the whole family was out there and they were working with it," he said. "When I came back is when I found out that the event happened."
He said the aircraft was intended to hover around 20 feet in the air and was not intended to carry people.
"Obviously, something went wrong with that."
Friedland described his neighbors as "a great family."
"They're unusual, yes, of course. He's sort of a scientist-slash-inventor. They're storm chasers -- they go after tornadoes, hurricanes, things like that," he said.
"He's a great kid," Friedland said of Falcon. "We see him a lot and they come over and they're always friendly."
