A child has died in a stabbing attack in the Blue Mountains, with two other children and a woman in hospital in critical condition, New South Wales police say. This was reported by Qazaqyia.kz citing The Guardian.

In a statement on Sunday afternoon, police said emergency services responded to reports of three children and a woman with stab wounds in a vehicle on Waratah Road, Valley Heights.

"Officers from Blue Mountains Police Area Command have been informed that several members of the public performed first aid on the woman and three children whilst contacting Triple Zero," they said in a statement.

One of the children was located deceased in the vehicle.

Police said NSW Ambulance treated the two children, who are believed to be under five, and the woman, believed to be in her 40s, at the scene before they were taken to Westmead hospital, where all three are listed as being in a critical condition.

"A crime scene has been established, and police are not looking for any other people at this time," they said.

Police are urging anyone with information or mobile phone or dashcam footage of the incident to contact Crime Stoppers.

The incident occurred in the Valley Heights area of the Blue Mountains. Police have established a crime scene and are conducting an investigation. At this time, authorities say there is no ongoing threat to the public and police are not looking for any other people.

Local residents reported seeing emergency services and police officers at the scene. The circumstances and cause of the incident remain unknown.

As part of the investigation, police are gathering witness statements and collecting evidence from the scene. The investigation is ongoing.