Witnesses to a Sydney stabbing that left a woman seriously wounded pounced on the alleged offender and performed a citizen’s arrest.

The woman, 47, was arguing with a 21-year-old man in Randwick on Wednesday afternoon when he allegedly stabbed her several times in the head and upper body with a paint scraper.

He then took off but was apprehended by members of the public in an adjacent street, police said.

The woman was taken to hospital in a serious but stable condition.

The man was also taken to hospital, under police guard, before a trip to Maroubra police station ended with him being charged.

He is due to face Waverley Local Court on Thursday on a charge of domestic violence wounding with intend to cause grievous bodily harm.

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-AAP