Seven-year-old James Delorey disappeared on Saturday afternoon. (Cape Breton Regional Police)

A seven-year-old autistic boy who disappeared from his Cape Breton home two days ago was found alive, unconscious, suffering from hypothermia and huddled in an area of thick brush and snow on Monday.

Searchers found James Delorey in the woods about 1.3 kilometres from his home in South Bar, near Sydney, N.S., at approximately 12:15 p.m., said Cape Breton Regional Police Chief Myles Burke.

"James is in a very serious situation at this point," he said.

Paramedics and search-and-rescue teams managed to move the boy, who is in critical condition, to a waiting EHS LifeFlight helicopter that was able to land about 400 metres away from where he was found.

Nearly four hours after being discovered, the boy was airlifted to the IWK Health Centre in Halifax.

"With the paramedics doing their job and getting the 400 metres to where the chopper landed, it took an extreme amount of time and a lot of effort on their part to extract him from the area he was located," said Const. Kenny Routledge.

"With the seriousness of his condition, moving him very slow and precisely is imperative," he said.

Paul Maynard, spokesman for Nova Scotia Emergency Health Services, said earlier Monday that the boy had "a faint pulse" and was hypothermic.

Halifax Regional Search and Rescue volunteers had found Delorey by a brook near Kilkenny Lake. Paramedics were flown to the scene in a helicopter to assess the boy's condition.

Followed the family dog

Delorey, who doesn't speak, wandered out of the family backyard at about 2 p.m. on Saturday. He was apparently following the family's dog, named Chance.

The boy was wearing only jeans, a shirt and a vest — nothing to prepare for the cold temperatures and heavy snow that hit the area that day.

On Monday morning, Chance returned home. Search and rescue officials said a team was working to trace the dog's tracks when another team located Delorey in the direction they were travelling.

"We were searching in areas that we felt had the highest probability that he would be found," said Michael Murray of Halifax Regional Search and Rescue. "Looking at some of the statistical information we have about children like him and his age, we were able to determine roughly how far we might expect … to find him."

Murray said while no one will know for sure how the boy survived in such cold, being in thick brush may have helped.

"Perhaps with a dog, [he] was able to sort of huddle close to the dog and that perhaps gave him enough body heat to survive," said Murray.

"The conditions out there were very difficult to search in. We had a very young child so there was a great sense of urgency."

The massive search effort included search-and-rescue teams from around Nova Scotia, as well as hundreds of community volunteers.

Paul Vienneau, the search commander for Cape Breton Search and Rescue, said missing children usually prompt the biggest response in a search.

"This search pulled all the teams together in the province," he said. "The volunteers from the fire department, the public, it all came together. It was fantastic."