An elderly farmer was shot dead and his wife was wounded when they were attacked at their farm in Tolwe on Wednesday morning, Limpopo police said.
Lt-Col Ronel Otto said US hunters, who were staying there as guests, heard shots at the main house on the farm, which is situated in the Baltimore area.
They went to investigate and saw four men escaping through a bathroom window.
They found Johan van Rensburg dead and his wife Claudia in a serious condition.
"She was then taken to the local hospital," Otto said.
She said the gunmen gained entry into the house by breaking the bathroom window.
The motive for the killing was unknown and police were looking for those responsible, Otto said.