The incident unfolded at a popular holiday park at Mumbil, south-east of Dubbo, just before 11am yesterday.
Police said the one-year-old was treated by paramedics at the scene before being airlifted to the Children’s Hospital at Westmead in a critical condition, where he later died.
Police confirmed the toddler died in hospital about 5pm yesterday.
A crime scene was established and an investigation into the incident has commenced.
Witnesses have been urged to contact police.
