The disturbance started at a Savige Street house just after midnight, with neighbours reporting hearing yelling, which prompted several calls to police.

The argument, which is understood to concern grievances over a relationship, escalated when a 21-year-old woman, Emma Thost-Hedge, allegedly started hitting a blue Mitsubishi parked in a driveway. The driver of the Mitsubishi tried to flee, reversing quickly back out of the driveway. But as he reversed, he hit his friend, Benjamin Tonkin-Smith.

The car came to a stop on the opposite side of the street, although it is not clear whether Mr Tonkin-Smith was dragged across the roadway.

Police arrived at the scene to find Mr Tonkin-Smith lying on the ground with critical injuries. They called paramedics and he was taken to Canberra Hospital.

But Mr Tonkin-Smith was soon pronounced dead by hospital staff.

The driver has been co-operative with police. No charges had been laid over the death by late Saturday afternoon.

Ms Thost-Hedge was charged with property damage and was bailed by the ACT Magistrates Court on Saturday morning.

It is believed she was in a relationship with the victim's sister, Courtney Tonkin-Smith. Benjamin Tonkin-Smith was described in court as a ''mutual friend'' of the driver and Ms Thost-Hedge.

Residents of the quiet suburban street spoke of their shock.

Michael and Marion Burgess were woken up by a guest who told them police were at the door. They were then told the Mitsubishi sedan and a critically injured Mr Tonkin-Smith were on their lawn. ''It was a shock knowing someone died, or almost died [outside our home],'' Mr Burgess said.

None of the residents reported hearing any disturbances from the house in the past.

Investigators were attempting to reconstruct the circumstances of the crash early Saturday morning and trying to determine the speed of the car.