Police probe suspicious SA house fire

A house has been significantly damaged in a suspicious fire in a seaside suburb of Adelaide.

Emergency services were called to the Norongo Street property in O'Sullivan Beach about 12:30am on Wednesday and managed to bring the blaze under control quickly, but not before it caused about $50,000 worth of damage.

The residents were not home at the time.

The fire is being treated as suspicious and investigators remain on the scene.