One man burned to death in a house fire in Diepsloot Extension One, said Johannesburg emergency services spokesman Synock Matobako.

On waking on Sunday morning, residents saw smoke coming from the house.

They forced open the door and found the man had burnt to death.

"He was alone in the house as his mother went to church last night," said Matobako.

In Heriotdale, south of the city, 100 shacks burned down around midnight on Saturday, said Matobako. The fire displaced 150 people. Non-governmental organisations were providing soup to those affected. They were also trying to organise blankets.

The cause of both fires was not known, he said.

Two people were burnt to death in a house in Benoni, Ekurhuleni on Saturday, paramedics said on Sunday.

Spokeswoman Vanessa Jackson said the cause of the fire was not known.

"Paramedics arrived at the scene and the residential structure was well alight."

She said by the time the blaze was put out, the man and woman were already dead.