A Sydney woman is struggling to survive after she was allegedly shot multiple times in the head with a nail gun in the city's west on Christmas Day.

Australian emergency services were called to a home in Bonnyrigg Heights about 10.30pm to reports of an injured woman.

Police were told the 50‑year‑old woman became involved in an altercation with her 20‑year‑old son, before she was allegedly shot in the head a number of times with nails from a nail gun.

Police say he fled.

Australian police arrested a 20‑year‑old man following the Christmas Day nail gun attack.

Paramedics treated the woman for lacerations to her face before she was taken to hospital where she is undergoing surgery and remains in a critical condition.

[Source: Sydney Morning Herald]