Father and daughter killed in rideshare crash

A father and his 11-year-old daughter, who were killed while riding in the back seat of a rideshare vehicle, died moments after their driver took a right-hand turn, police say.

Emergency services were called to Milperra in western Sydney on Sunday night after reports a car and ute had crashed.

Police said dashcam footage showed the rideshare driver turning right at an intersection before the Toyota sedan is hit by an oncoming Toyota HiLux which struck the back left passenger door.

The sedan rolled, trapping the 52-year-old male driver and his three passengers inside.

A 41-year-old man and his daughter died at the scene while his nine-year-old son was taken to hospital in a critical condition.

The driver was also taken to hospital in a serious but stable condition.

The 19-year-old driver of the ute was treated at the scene for minor injuries before also being taken to hospital.

NSW Police Assistant Commissioner Brett McFadden said the rideshare vehicle turned right at the intersection when it "wasn't safe to do so".

"I'm satisfied the traffic control lights were working at the time and the driver did undertake a right-hand turn and on the dashcam there are clearly other vehicles visible coming from the opposing direction," he told reporters on Monday.

"It was a clear single green traffic controller ... there was no particular arrow.

"I'm satisfied that it wasn't safe to do so (turn right)."

Mr McFadden said police would be investigating whether the 19-year-old was driving at a speed greater than the 70 km/hour limit, while the rideshare driver would also be interviewed following his release from hospital.

"All drivers in these serious crashes, their behaviour is looked at in a very minute and detailed way and it is (speed) one of the factors we will be looking at," he said.