Police defend shooting knife-wielding woman

New South Wales police are defending the actions of a female officer who shot a woman in Sydney's west overnight.

Police were called to North Parramatta just after 1.30am after reports of a woman threatening a man with a knife.

It is alleged the 48-year-old woman lunged at the female police officer, who then fired several shots.

The woman was taken to Westmead Hospital, where she remains in a serious but stable condition.

A 23-year-old male was also taken to the hospital and treated for a neck laceration sustained in the initial confrontation with the woman.

Acting Police Assistant Commissioner Karen Webb said attempts to subdue the woman with capsicum spray failed.

"Upon arrival the woman allegedly threatened police with a knife, refusing to surrender the weapon," she said.

"Capsicum spray was used in an attempt to subdue her.

"The female continued in a threatening manner, lunging towards police and officers discharged a number of a firearms."

A critical incident investigation team is now examining the circumstances surrounding the shooting.