Three people, including two police officers, have been injured in a car crash in Sydney's west overnight.

Police attempted to stop a white VW Golf travelling in Dean Park for a random breath test and gave chase when the driver allegedly failed to stop about 10.15pm.

The pursuit ended shortly after when officers lost sight of the car.

As officers patrolled the area, a marked police car from the Nepean Area Command and a Holden sedan became involved in a head-on collision on Debrincat Avenue in North St Marys.

The driver of the Holden, a 47-year-old man, suffered injuries and has been taken to Westmead Hospital in a serious but stable condition.

A 25-year-old male police constable, the driver of the police car, and a 25-year-old female senior constable were treated by paramedic

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