A 13-year-old girl has watched on as her father was stabbed to death in a domestic dispute in Sydney’s north-west.

Police responded to a Triple Zero call by the 13-year-old during a domestic spat inside home, now a crime scene, on Engadine Avenue in North Richmond.

There they found a man in his 40’s dead, with stab wounds.

His mother-in-law, in her 60’s, has been taken to hospital with critical neck wounds.

The wife of the deceased has minor injuries.

Another 13-year-old girl, believed to be a friend of the teenager, also witnessed the altercation.

Detective Superintendent Jim Stewart says it was a horrific scene for police, let alone a teenage girl.

Neighbours say there was no indication of trouble within the home, however, police say the family was known to them for domestic related matters.