Sydney home collapses, three people escape

Three people have watched the roof and side of their house collapse in Sydney's south and there's fears more of the property might also come down.

The occupants safely left the Mascot house after it started to give way on Wednesday afternoon and are waiting in a neighbour's home, a NSW Fire and Rescue spokeswoman told AAP.

"The side of a house has partially collapsed and the rear is threatening to collapse," she said.

Two fire crews and another two heavy rescue specialist crews are trying to stabilise the home.

They're keeping people away from the area and have isolated the home's gas and power.