Police allege mother behind Blue Mountains stabbing attack on three children that left one dead

Bystanders found all four on the side of the road at Valley Heights on Sunday with stabbing injuries

Police have alleged that a mother was behind a stabbing attack on three young children that left one dead and two others fighting for their lives in hospital.

Bystanders were first on the scene after finding the three children and the woman with stab wounds inside a vehicle at Valley Heights in the Blue Mountains , west of Sydney, on Sunday afternoon.

One young child died at the scene despite witnesses rushing to help, delivering first aid while waiting for emergency services to arrive.

The alleged domestic violence incident came at the end of a horror weekend across New South Wales , after three women were allegedly murdered inside their homes within a 12-hour period on Saturday.

The police deputy commissioner Peter McKenna described the past two days as devastating.

“It’s a horrific and tragic weekend and it’s like one that I don’t remember in my career,” he told Nine’s Today on Monday.

“Those three … plus the no-more-tragic situation that we had in the Blue Mountains. Put them all together and it’s unfathomable.”

Paramedics treated the mother and children at the scene on Sunday before taking them by road to Westmead hospital and Westmead Children’s hospital in a critical condition.

“The two children and their mother are in a critical condition,” McKenna said.

“The mother is the suspect in this matter, for domestic related homicide, and that investigation is ongoing.”

McKenna told reporters on Monday the woman remained in a critical condition and police had “to wait for the medical side to play out”.

“If she recovers from those injuries, certainly our people … will be intent on charging [her] with homicide,” he said.

Hours after the incident, NSW police Supt John Nelson said the father of the children had been notified.