A toddler has died after she was struck by a car being driven by her mother in Sydney’s south-west.

The two-year-old girl was hit by the family car, a Kia vehicle, as it reversed at the rear of a mechanic business on Beamish Street in Campsie just before 11am.

After hearing hysterical screams for help, worker Freddy Farhat ran outside to find the toddler lying injured in the carpark.

The incident took place on Beamish Street, Campsie.

“I’m just shocked. (They’re) a great family, a tight-knit family,” Mr Farhat told 9NEWS.

“To see something like that happen … it’s not good, especially at this time of year.”

Emergency services arrived within three minutes to find family members performing CPR on the two-year-old who was in cardiac arrest with life-threatening injuries to her head, chest and neck.

Police attend the scene outside the Campsie business.

The child was taken to the Royal Children's Hospital.

Police escorted an ambulance which took her to Sydney Children’s Hospital, where she later died.

“This is a horrific scene for not only the driver but for all those involved, and particularly for police and emergency services,” Superintendent Adam Whyte said.

“The driver was absolutely hysterical, as you would imagine.”

It comes after news a baby was left in a critical condition after being hit by a car reversing out of a driveway in Melbourne .

The 43-year-old mother has been taken to hospital for mandatory blood and urine tests.

Police are continuing to investigate the incident and it remains unclear how the toddler ended up behind the vehicle.