Sydney firefighters are working to contain a blaze at a service station in the city's south-west.

A New South Wales Fire and Rescue spokesperson said the servo was well alight when crews arrived.

Hoxton Park Road at Liverpool has now been closed to traffic in both directions.

Motorists are being warned to avoid the area.

It is believed to be the same BP service station where half a dozen 200kg LPG gas cylinders caught fire and causes major damage back in August.

That incident caused nearby shops to be evacuated, school to be put on evacuation alert.

Firefighters are also battling a bushfire that is threatening homes in Sydney's northwest.

Six fire engines were sent to Lane Cove National Park at North Ryde just after two o'clock this afternoon.

Meanwhile, a blaze is burning out of control near Crescent Head on the state's mid-north coast.

Nearly a hectare of bush has been burnt out at Beranghi Road, as the fire heads east.

Several fire trucks are on scene as RFS crews instruct residents as to how to protect their homes.

A bushfire has also closed southbound lanes of the Pacific Highway at Tea Gardens, north of Newcastle.

Latest From 7News