A teenage P-plate driver has been charged with dangerous driving after a pregnant woman and her unborn child were hit and killed in a two-car crash.
Ambulance paramedics treated the woman, who was eight months pregnant, at the scene before she was taken to Sydney's Westmead Hospital in a critical and unstable condition but she and her baby were unable to be saved.
The woman had been walking with her husband and three-year-old son when she was struck by a vehicle at the entrance to a car park at Hornsby in the city's northwest on Friday evening.
A 19-year-old man behind the wheel of a BMW and a 48-year-old male driver of a Kia station wagon were uninjured.
Both were taken to Hornsby Hospital for mandatory testing.
Traffic and Highway Patrol Command assistant commissioner David Driver described the incident as a "terrible, terrible story".
"Any serious crash is very confronting for first responders, and it’s particularly tragic when people pass away, and indeed when there are children involved," he said.
"The matter was under investigation, and the drivers involved were arrested for the purpose of mandatory testing.
"But when the (woman) succumbed to her injuries, police arrested the gentleman at his home address and he was subsequently charged with those offences."
Police are expected to allege that the Kia was struck from behind by the BMW causing it to crash into the woman.
The younger driver was arrested at a home in Wahroonga in the early hours of Saturday and questioned by detectives.
He's been charged with dangerous driving occasioning death including causing the loss of a foetus and refused bail to appear before Parramatta Local Court on Saturday.
Anyone with information about the crash or who was in the area at the time and recorded dashcam or mobile phone footage is urged to come forward to police.
Police believed the incident was captured on CCTV, but the assistant commissioner would not comment further.
A critical incident investigation was also under way on Saturday after the death of a motorcyclist who was being pursued by highway patrol officers, at inner city Zetland.
An attempt was made to stop the bike on Southern Cross Drive shortly before midnight on Friday, with the chase activated when the rider refused to pull over.
Police say the motorcycle crashed into the rear of a van in front, a short time later.
The rider was treated by police before paramedics arrived but died at the scene.
A critical incident investigation team will examine the circumstances surrounding the incident, which will be the subject of a review by the force's Professional Standards Command and overseen by the states Law Enforcement Conduct Commission.
