Police spokesperson Priscilla Naidu says the fire started shortly after midnight on Thursday, and razed the structure to the ground.
She says it is alleged that the family went to bed during load shedding and left a candle burning.
Naidu says when the mother woke up the shack had already started burning but she and her husband managed to escape through a window.
The couple's three children, 3-year-old Asciwalise Ngqina and his two sisters, 6-year-old Asipile and 11-year-old Ibanathi died in the fire.
Naidu says three other adults were also killed.
The mother who managed to escape the flames sustained burn wounds to both her arms and hands, while her husband sustained burn wounds on his face and arms.
Police say neighbours assisted in dousing the flames with buckets of water while waiting for the fire brigade to arrive.
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