A young girl who was meant to be enjoying a night at Disney on Ice is instead in hospital after being mowed down by a dirt bike.

Nine-year-old Elisabeth Bambina was playing with friends at Haydon Park, behind her home in Rosemeadow in Sydney’s southwest, when she was run over on Thursday.

WATCH THE VIDEO ABOVE: Hit and run leaves 9 year-old suffering.

Know the news with the 7NEWS app: Download today

A man riding an unregistered dirt bike allegedly sped through the park and struck Elisabeth as she rolled down a hill about 5.45pm.

The rider didn’t stop, leaving the nine-year-old with significant head and facial injuries.

She was treated at the scene before being rushed to The Children’s Hospital at Westmead in a serious condition.

The Year 4 student underwent emergency surgery on Thursday and spent hours in surgery again on Friday morning.

Plastic surgeons have also been called in to assess the extent of any permanent damage.

Elisabeth’s mother, who was interstate at the time, was flying home to be by her daughter’s side.

Her aunt, Brittany Rousell, is pleading for help to find the rider.

“She’s supposed to go to Disney on Ice tonight with her family, but now she’s having a surgery, not knowing the outcome, what’s going to happen,” Rousell said.

“Just gutting that they’ve just left this port. What if she was by herself? She could have been dead. Which is just gut-wrenching that they’ve left a nine-year-old in that condition.”

NSW Ambulance Station Manager Abbey Gillam described the situation as traumatic for everyone involved, especially the young patient.

Police are calling for the rider to come forward.

“The rider would know that he hit the little girl, he did stop briefly, had a really brief conversation and rode off without helping the young child,” Deputy Superintendent Grant Healey said.

CCTV shows several trail bikes tearing through the park before the hit-and-run, with the fleeing rider reportedly seen wearing a white helmet.

“We desperately need the help of the community to tell us who’s riding the bikes, where the bikes are,” Healey said.