The Easter long weekend has been marred by a string of road fatalities across the country, with many involving motorcyclists.
In the latest incident, police found a car had crashed into an embankment after leaving the road at Merriwa in the NSW upper Hunter area on Sunday night.
Paramedics attempted to treat a man but he died at the scene.
A few hours earlier, emergency services were called to South West Rocks on the NSW mid north coast on Sunday afternoon.
They found a motorbike rider had crashed on the road before becoming trapped under a nearby vehicle.
Emergency crews worked to free him before he was treated by paramedics for critical injuries, but he was unable to be saved.
The same day, in far-north Queensland, a 31-year-old man lost control of his quad bike on a local road in East Palmerston, a rural farming area near Innisfail, on Saturday.
His green Kawasaki bike struck a pole and he was pronounced dead at the scene.
Nearly two hours later, a black Honda motorbike collided with a Kia Cerato in Thornlands, about 30km southeast of the Brisbane city centre.
The 18-year-old rider died after being transported to hospital with critical injuries. The Kia driver was uninjured.
In South Australia, two men, one riding a Honda motorcycle and the other a Suzuki, died in a collision at Paracombe in the Adelaide Hills about 2.30pm on Saturday.
Another South Australian man, riding a Harley Davidson, died on Friday after he crashed into a traffic light, police said.
Meanwhile, in NSW, a man in his 40s travelling with several other motorbike riders, crashed on the Monaro Highway near Cooma on Friday and died at the scene.
In other road deaths, a mother-of-four from Victoria was killed after a crash in Queensland.
The 51-year-old was a passenger in a Ford hatchback travelling on School Road in Logan Reserve, south of Brisbane, about 9pm on Saturday when her car was hit head-on by a Ford Falcon utility.
The victim, who had been returning from a family celebration, died at the scene.
Her 21-year-old niece sustained serious leg and back injuries, while a one-year-old child in the car miraculously escaped harm.
Chief Superintendent Mark Wheeler said on Nine's Today program that there had been six road deaths in Queensland alone since Thursday.
More than 1336 people have died on Australia's roads in the 12 months to February, according to the federal government figures, marking a 4.4 per cent increase from the same time the previous year.