Sydneysiders have been shaken awake after an earthquake hit just south west of the city.

The magnitude 3.5 quake struck near Appin, south of Campbelltown near the Nattai National Park, just after 6am on Sunday.

Geoscience Australia said the earthquake originated at a depth of 2km, with almost 250 people lodging “felt reports” with the agency.

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Concerned locals posted on social media after the quake, with one Douglas Park resident saying it “felt like a car hit my house”.

Others had similar experiences, also saying it felt as though something had smashed into their their properties.

“Thought a truck ran into our house. The house shook,” said another local.

“In Wilton (it) woke us up, freaked out at what was going on,” said another. More to come...