The sisters parents, Lars Falkholt, 69 and Vivian, 60, passed away when their vehicle collided with another on the Princes Highway on the New South Wales south coast, while the surviving two were rushed to St George and Liverpool Hospital in critical condition.
The third person killed by the crash was an unnamed man from Ulladulla who is reportedly 50-years-old.
NSW Chief Inspector Phil Brooks told reporters that the Christmas and New Year period was 'meant to be a time of happiness' but 'sadly for many this has resulted in tragedy.'
With this Insp. Brooks said police are urging motorists to be careful on the roads.
9News reports this is these deaths mark the 21st since December 15, the beginning of Operation Safe Arrival, the state's Christmas and New Year road safety campaign.
Our thoughts are with the all the people involved in this tragic event.