A father, who believed his wife had taken their three young children on a picnic, received a devastating phone call at work informing him that his five-year-old son was dead and the rest of his family was fighting for their lives. Police allege the 42-year-old mother stabbed all three children, aged five and under, while they were strapped into their car seats in Valley Heights, an area of the Blue Mountains, before turning the knife on herself.

The alleged attack occurred on Sunday afternoon. The five-year-old boy succumbed to his injuries, while his two younger siblings sustained critical wounds. The children were discovered after two cyclists and a passing motorist stopped on Waratah Road and attempted to provide assistance. Police described the scene as "barbaric."

The mother and her two surviving children were transported to Westmead Hospital and The Children's Hospital at Westmead, respectively, where they underwent surgery and remained in critical condition on Tuesday. Detectives intend to interview the mother about the incident if her condition improves, with a homicide charge anticipated.

The father, who has no known links to the Blue Mountains area, rushed to the hospital to be with his surviving children. He is receiving support from Sydney's Kenyan community, and the Kenyan consulate has confirmed it is assisting the family.

A local resident, Julie Sukkar, initially mistook the commotion near her home for a traffic accident. Upon investigating, she observed a four-wheel-drive vehicle with open doors and the children inside, while the mother was found nearby in bushes, reportedly yelling and thrashing. Ms. Sukkar noted the children's unsettling silence amidst the chaos. Police initially handcuffed the mother but later removed the restraints as she was taken by ambulance.

Police stated the family had no prior connections to the Blue Mountains and were not previously known to law enforcement. The wounds sustained by the mother are believed to be self-inflicted. The resident praised the quick actions of the individuals who stopped to help, suggesting their intervention may have saved the lives of the two surviving children.

If this story has affected you, please contact Lifeline on 13 11 14 or Beyond Blue on 1300 22 4636.