Three children have been hit by cars in the state since the start of the week.

A three-year-old boy is fighting for his life in hospital after he struck by a car on a street in Sydney’s west last night.

He was treated at the scene before being taken to Westmead Children’s Hospital, where he remains in a critical condition.

The man driving the car was taken for mandatory drug and alcohol testing.

Earlier in the week at Kellyville, a four-year-old girl was left with critical injuries when she and her family were run down by an alleged drink driver who’s also accused of texting behind the wheel.

The next morning, a nine-year-old girl was hit by a car at Lismore and died in hospital.