Six road deaths just days before Christmas

The road death toll has risen to six on the second day of Australia's Christmas holiday season.

A man died after his 4WD crashed into a bus, injuring a woman and a child, on a highway northwest of Toowoomba in Queensland on Thursday.

The car's passengers suffered abdominal injuries during the collision around 8.30am on the Warrego Highway near Okey, an ambulance spokesperson says.

They were taken to Toowoomba Hospital where they remain in a stable condition.

The coach's 18 elderly passengers and driver all escaped serious injury.

In regional Victoria, a woman died after a car flipped when the driver lost control on the South Gippsland Highway near Koonwarra.

The woman, who was a passenger, died at the scene while the male driver, aged in his 20s, was taken to hospital with minor injuries.

Police around Australia are increasing safety operations over the Christmas period, including stepping up drug and alcohol testing.

South Australian police on Wednesday conducted the first round of "pop-up" breath tests in metropolitan areas, targeting daytime drink driving between 12pm and 3pm.

Meanwhile, Tasmania Police research shows motorists are most likely to have an accident on Christmas Eve.

The danger period of noon to 8pm was identified by examining the state's crash statistics from the past five years.

* The national road toll period runs from 0001 December 23, 2015 until 2359 January 3, 2016, local times.