The boy and girl, 3, were rescued from the burning building by their domestic worker.

Marshall Security spokesperson Kyle van Reenen said that the alarm had been raised by neighbours, who had seen smoke billowing from the top storey of the home.

He said that medics and security officials had rushed to the scene.

"At this point in time it would appear that the fire was contained to a room on the second floor of the home… it was the room that the children were in," he said.

He said that a domestic worker had braved the fire and managed to get inside the room to rescue the toddlers.

"She got inside the room and got the kids out. The children are in a critical, but stable condition, and were treated at the scene by paramedics from Netcare911," he said.

Van Reenen said that, after the children were stabilised, they were transported by ambulance to a hospital for further treatment.

"The domestic worker was suffering from smoke inhalation and she too was transported by ambulance to the Addington Hospital."

He said the cause of the fire was unclear.

News24, Statement