Lieutenant Colonel Lesego Metsi confirmed that Daniel Black's family was on holiday at a resort near Bronkhorstfontein when their chalet was flooded and three of the five family members were swept away by the river at midnight on Wednesday.
Black's wife and another child, 18, managed to escape the flood waters pouring into the house after the door was opened, by climbing onto furniture.
Metsi said Black held on to his 4-year-old boy as he and his 12-year-old son clung to trees to prevent being swept away.
The father and his small son became separated and at noon on Thursday rescue services found only him and his older son holding on to trees in the river.
"Police searched and the body of the 4-year-old was found a few kilometres away from the resort at 14:00."