Eighteen dead on our roads these holidays

Eighteen people have died on Australian roads this holiday period, including a 10-year-old boy and a elderly man in separate NSW incidents.

The 10-year-old boy died in hospital after a head-on collision 32km northeast of Grafton, around 4.20pm on Wednesday.

The driver and other three passengers in the car he had been in were injured.

Earlier a man in his 70s became the victim of a hit-and-run in Sydney's southwest.

The man left a family home and was about to get into his parked car when a white van travelling north hit him and continued to drive from the scene, police say.

It's been a horror couple of days for NSW, with a three-year-old girl having to be put in an induced coma after being ejected out of a car that rolled.

A 24-year-old woman died in the crash near Dubbo on Tuesday, while the car's driver, a 26-year-old man suffered non-life threatening injuries.

There have been six fatalities on NSW roads during the holiday period, the nation's highest.

On Tuesday a man lost control of his car when it swerved off a road near Donald in Victoria and flipped, while in Adelaide two men lost their lives in separate crashes.

A male driver died after his car smashed into a tree in Morphett Vale while a motorcyclist died after a crash in South Australia's mid north.

The two deaths were the first for South Australia during the holiday period.

In Queensland, tributes were flowing for young boy who died after he was hit by an allegedly drunk driver near Brisbane on Christmas night.

Flowers, soft toys and candles were being placed at the scene of the crash that took the life of nine-year-old Josiah Sisson.

He was looking at Christmas lights with his family in Springwood when he was hit by the 24-year-old driver on Sunday.

The AAP national road toll period runs from 0001 December 23, 2016 until 2359 January 3, 2017, local times.