A woman and a 10-year-old boy were killed in a traffic accident at Corrigin, in the Wheatbelt of Western Australia, after a trailer was plowed into a parked car.
Three other children were seriously injured and are being treated in the hospital.
The woman and the four children were parked in a Holden Commodore on the side of Brookton-Corrigin Road around midnight on Sunday.
The car that had towed a trailer had ran out of petrol and the male driver had left to walk to Corrigin to get petrol.
The police said that a semi-trailer, driven by a 46-year-old man and dragging grain trailers, made a turn and collided with the parked car.
The car and the trailer were thrown overboard in a paddock by the force of the impact.
The woman and the boy died on the spot, while the three other children – 8, 5 and 3 years old – were flown by helicopter to the Perth Children's Hospital.
The police said the driver of the car, a 27-year-old man, walked along the Brookton-Corrigin Road about 11 kilometers west of Corrigin, about 220 kilometers northwest of Perth.
A spokesman for the hospital said that the condition of all three was serious but stable.
The police have closed roads in the area and remain on the spot.
The Brookton-Corrigin Road is closed in both directions between Rigby Road and Bulyee Road.