Two adults and two children died in two separate fires in Johannesburg, emergency services said on Friday.

Spokesperson Percy Morokane said one fire occurred on Thursday night in Diepsloot, and another on Friday morning at the George Goch informal settlement.

"In the first incident, a mother and her three children were asleep when their shack caught fire, allegedly due to a candle that was left burning," he said.

"The mother and her five-year-old son were burnt beyond recognition and her two other children, two boys aged seven months and nine years respectively, were taken to the Tembisa Hospital, having suffered over 60 percent burns," he said.

The seven-month-old baby died on Friday morning.

About 20 shacks were burnt to the ground on Friday morning at the George Goch informal settlement.

"A woman was burnt beyond recognition. She was alone in her shack and no further injuries or deaths were reported," said Morokane.

"A candle that was left burning is suspected to be the cause."

A disaster management team was assisting with relief aid.