A pedestrian is in a critical condition after he was hit by a car in Sydney’s Hills District.

The 34-year-old man was trapped under the van that struck him on Ferndale Ave at Carlingford about 12.30pm on Sunday.

The driver of the car fled on foot, NSW Police allege.

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Emergency services worked to free the 34-year-old man from under the van before treating him for critical injuries.

He was taken to Westmead Hospital fighting for life.

Police began a search of nearby bushland, and arrested a 29-year-old man they allege is the driver.

He was taken to Castle Hill Police Station, but no charges have been laid at this stage.

Investigations into the crash are ongoing and anyone with information is urged to contact Crime Stoppers.