The bodies of a woman and young child have been pulled from the ocean near the border of Victoria and South Australia, as authorities work to locate a second missing child.

South Australia Police on Monday evening said officers were called to an area west of Port Macdonnell - about 27 kilometres south of Mount Gambier - after reports a vehicle had been found empty with its engine still running.

“During subsequent enquiries, police tragically located two bodies in the ocean,” police said.

“The body of a woman and a toddler have been recovered.”

Police confirmed the woman has been identified as a 36-year-old from nearby Compton, and the toddler is her child.

The search for a second child is continuing, with police holding “grave concerns” for the safety of the “infant”.

“Detectives from Major Crime Investigation Branch and specialist officers from Forensic Response Section are travelling to the scene,” police said.

It is understood emergency service helicopters from both Victoria and South Australia were called in to assist with the search.

Police are urging anyone who may have seen a white Isuzu MUX, SA Registration S592BJR to contact Crime Stoppers online at www.crimestopperssa.com.au or on 1800 333 000.

“Anyone who may have captured the vehicle on dashcam footage is also urged to contact police.”

**More to come. **