Son allegedly shot mum in the head with nail-gun on Christmas Day

Police were called to the scene after the 50-year-old woman was severely injured. Photo / Bill Hearne News Corp Australia

A Christmas Day celebration in Sydney's west turned into a scene of horror after a mother was allegedly shot multiple times in the head with a nail gun by her own son.

After hearing reports that the 50-year-old had been severely injured, emergency services rushed to a home on Messina Crescent in Bonnyrigg Heights about 10.30pm last night.

Police allege the woman and her 20-year-old son became involved in an "altercation", before she was struck multiple times in the head with projectiles from a nail gun.

The man fled the scene.

She was treated at the home by paramedics for injuries to her face, before being taken to Liverpool Hospital where she underwent surgery. She remains in a critical condition.

Another man was treated at the scene for shock.

"Officers from Fairfield City Police Area Command established a crime scene and commenced inquiries into the circumstances surrounding the incident," NSW Police said in a statement.

At about 3.45am this morning, police confirmed a 20-year-old man had been arrested by officers near the crime scene and taken to Fairfield Police Station.

The shocking alleged attack comes as Australians are being encouraged to take care of themselves and others this festive period, by watching their social media use and looking out for signs of domestic and family violence.

Federal Labor MP Linda Burney said rates of domestic and family violence typically increased over Christmas, with calls to one helpline spiking by 22 per cent last December.

She urged Australians to look out for family, friends and workmates who might be victims, noting that violence against women could be physical, emotional, psychological and sexual.

"We need to look for more than bruises — manipulation, threats, coercion, humiliation, stalking and controlling behaviour are all forms of domestic violence," Ms Burney said.

"If something seems wrong with someone you know, ask if they are OK. Don't leave it to chance."

— with wires