A four-year-old boy named Gus has been missing from a family homestead in South Australia's mid-north since Saturday evening, prompting an extensive and ongoing search effort.

Gus was last seen around 5pm on Saturday near his home, located approximately 40 kilometres south of Yunta and 200 kilometres east of Port Augusta, wearing a grey sun hat, a blue Minion T-shirt, light grey pants, and boots.

He is described as a Caucasian boy with long blond curly hair, and his clothing includes a grey sun hat, a cobalt blue long-sleeve T-shirt with a yellow Minion, light grey pants, and boots.

Authorities emphasize the urgency of the situation due to the potential dangers of exposure in the open environment, regardless of weather conditions, especially since Gus is comfortable outdoors, which could increase the risk of him getting lost or harmed.

A large-scale search operation has been underway, involving police, Polair, infrared cameras, SES volunteers with trailbikes, ATVs, drones, and a ground search covering a 2.5km radius from the last sighting.

The search efforts intensified on Sunday, with multiple resources including police helicopters with infrared technology, ground teams, SES volunteers, trailbikes, ATVs, and drones actively searching the area.

Despite continuous efforts through Sunday and into Monday morning, Gus has not yet been located, but authorities remain hopeful for a positive outcome.

Police are very concerned about Gus’s safety and are using every available resource to find him, including deploying additional units such as the Mounted Operations Unit and water police to search dams and tanks on the property.

Additional resources, like the Mounted Operations Unit and water police, have been involved in the search, with police remaining hopeful despite the challenging circumstances.

Water police are conducting searches of dams and tanks on the property, adding to the extensive ground and aerial efforts.

Authorities have urged anyone with information to contact Crime Stoppers at 1800 333 000 to assist in the search.

The primary goal remains to find Gus safe and well, and authorities continue to emphasize the importance of community cooperation and vigilance.

Deputy Commissioner Linda Williams stated they are 'very concerned' for Gus and are utilizing all available resources to locate him, reflecting the seriousness of the situation.