University of Chicago Medicine Comer Children's Hospital spokeswoman Lorna Wong said the 6-year-old Sterling boy was responding to simple commands and appeared to be reacting well to a ventilator, the Chicago Tribune reported.
The boy, whose name had not been released, was trapped for more than 3 hours Friday afternoon in what appeared to be a sinkhole on the slopes of Mount Baldy at the Indiana Dunes National Lakeshore, the Chicago Tribune reported.
Park spokesman Bruce Rowe said the boy was found a few feet beyond a rope cordoning off a section of the dune where grass and other plants were being replaced, the newspaper said.
Rowe said the boy possibly survived so long because an air pocket formed as the sand collapsed around him.
"I don't know if [officials] physically saw an air pocket, but that's what we're all presuming there had to be for him to be alive," Rowe said.
The child was pulled to safety by a firefighter who was among more than 30 people involved with the rescue effort, which also included use of an excavator, officials said.
"His parents want to extend their deepest thanks to the Michigan City fire and police departments and all the authorities, private companies and individuals who contributed to the rescue effort," Wong said, in a statement. "They also ask that people include this little boy in their prayers."
Rowe told NBC News earlier the type of incident was unprecedented in the park.
"This has not happened before, and we will certainly not let people on the dune until it is safe," Rowe said.
Officials estimated the hole at more than 30 feet deep and apparently was formed naturally under a rotted tree, WRTV-TV, Indianapolis, reported.
The boy's frantic parents tried to get him out, but that only caused a large slide of sand on top of him.
WGN-TV, Chicago, said a private excavation crew had to be brought in with heavy equipment to remove the mounds of sand and free the child.