Police are guarding a man in hospital after he allegedly ran a red light, fatally struck a woman in another car and drove off in Sydney's south-west on Sunday.
Crash investigators allege the 20-year-old driver smashed into a Toyota Yaris at Prestons about 9pm.
A woman, 57, was taken to Liverpool Hospital but was pronounced dead on arrival.
Her husband, 55, has been treated for shock.
Police Inspector Adam Powderly said it was devastating to see a family ripped apart just days before Christmas
"When these incidents happen at any time of the year it is devastating," Inspector Powderly said.
"But when it's the festive season it really hits home and that family has been torn apart."
Police said initial inquiries suggested the 20-year-old was driving a Landcruiser in a northerly direction along Bernera Road, when he failed to stop at a red light and drove through the intersection with Wroxham Street.
"It subsequently collided with the passenger side of the Yaris, which then crashed into a traffic light pole," a police spokesman said.
The driver of the Landcruiser allegedly ran from the crash before police arrived, prompting a search of Bernera Road and nearby streets.
A resident later found the driver hiding in the front yard of a house on Wroxham Street and called police.
Police arrested the driver and he was later sedated at hospital and treated for minor injuries.
Mandatory blood and urine tests have been taken but charges were yet to be laid on Monday afternoon.
Inspector Powderly said police were trying to establish whether the driver was the only person in the Landcruiser at the time of the crash.
He asked anyone with any information to contact police through Crime Stoppers on 1800333000.
