A fire has caused more than $1 million worth of damage to a mansion in Adelaide’s south-east.

The Metropolitan Fire Service (MFS) said seven occupants were able to evacuate before they arrived.

Firefighters had to kick down a door while rescuing two dogs in the property on Netherby Avenue at Netherby.

The MFS was called about 10pm on Monday and found the house ablaze, with its roof collapsing.

Up to 45 firefighters fought the fire during pouring rain, stopping it from spreading to neighbouring properties.

Fire cause investigators will go to the scene of the fire, which destroyed 70 per cent of the house, on Tuesday morning.