A house and car have been set on fire and shot at in Sydney's south-west overnight.

At about 12.45am, emergency services were called to Wendy Close, Cabramatta.

They found a house and a white Toyota station wagon, both alight.

Firefighters were able to quench the blaze, but not before the house and car both sustained significant damage.

Police were also told multiple gunshots were heard.

They found bullet casings at the location.

A 57-year-old woman was treated for smoke inhalation at the scene.

Three other occupants of the home were unharmed.

An investigation is underway and anybody with information is urged to contact Crime Stoppers on 1800 333 000 or online .

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