An extensive search for an “adventurous” four-year-old boy who vanished while playing in sand at his family’s isolated sheep grazing property has continued through the night and remains ongoing, police say.

Police on Monday said they would “throw everything” at the search to find the boy, known as Gus, after he went missing on the remote outback property, about 40 kilometres south of Yunta in South Australia’s Mid North, about 5pm on Saturday.

SA Police said its helicopter was on its way to the area this morning, while Commissioner Grant Stevens said more than 100 people — including police, SES personnel and community volunteers — were assisting in the search.

“This is a community effort to see if we can find this little fella,” he said.

“It is a large property, and on face value it looks like it would be relatively easy to search but it is proving challenging and there are lots of places a small child might find themselves which would be hard for us to identify as easily as people may think.”

He said police believed Gus was still on the property, had not been taken and that releasing his image would serve no purpose in the search.

SA Police Commissioner Grant Stevens is standing and wearing a full navy blue police uniform including police hat

SA Police Commissioner Grant Stevens is hopeful Gus will be found. (ABC News: Dean Faulkner)

Earlier, Commissioner Stevens said there were no “positive updates at this stage”, police were “maintaining that effort and hoping for good news”.

“We’ve got police, emergency services and community members conducting an intensive search — we’re using police aircraft, drones, our horses have been up there, we’ve got search controllers up there,” he said.

“It’s a methodical process to see if we can find this little fella.

“We’re very lucky with the weather … [so] everything is in Gus’s favour so we’re looking as actively and intensively as we can.”

Conditions in the area are expected to be partly cloudy on Tuesday, with the slight chance of a shower south of Yunta and a top of 22C.

Temperatures in the area reached the high 20s on Monday, but police were hopeful Gus’s clothing — a long-sleeve cobalt blue shirt with a yellow Minion picture on the front, light grey long pants, broad-brimmed hat and boots — would have offered protection both during the day and overnight.

Superintendent Mark Syrus, officer in charge of the Yorke and Mid North region, said the weather would have been “uncomfortable” for Gus.

“He was dressed well for sun conditions and we are hoping that served him well over those cold nights as well,” he said.

The desperate hunt for the boy at the family’s sprawling 6,000-hectare sheep grazing property began after his grandmother noticed he was missing from the sand where he had been playing, police said.

An aerial view of dry, arid ground with dirt tracks where four-year-old Gus went missing

Missing boy Gus disappeared on his family’s expansive and isolated property south of Yunta. (ABC News: Daniel Taylor)

Superintendent Syrus said there were about 3,000 sheep grazing on the “very isolated” and arid property, where goats, kangaroos and wallabies could also be found.

“As you can see, it’s pretty low-lying, undulating countryside,” he said.

“There’s some bluebush, which you would anticipate would be pretty easy to see, but as you can see from the enormity of the property here, it’s expansive.

“That’s why we’ve put as many resources as we possibly can into finding young Gus.”

Superintendent Syrus said the search was being guided by the expertise of the property owners and neighbouring landholders, while locals had combed the area on motorbikes.

A helicopter and drones have scoured the area from the sky, while police divers have checked water tanks and the dams on the property where water was present.

Dirt bikes and emergency services cars are lined up on dry, arid land.

The search for the missing four-year-old boy, known as Gus, began on Saturday. (ABC News: Daniel Taylor)

Superintendent Syrus said “fortunately”, many of those dams were dry and said Gus was not known to gravitate towards water.

He said initial searches also focused on workshops and sheds on the property.

Superintendent Syrus said it was not suspected anyone had taken the boy, saying the “only people who would travel on this road are station owners” or those who serviced the area.

He said it was “unusual” for Gus to have wandered off and said the boy “normally stays within the confines of the area”.

“But, who knows what goes through a four-year-old’s mind?” he said.

“We understand he’s a pretty quiet sort of lad, but he is, as you know, a country lad and he’s pretty adventurous as well.

“But him moving out of the area is a little bit unusual.”