A driver has been arrested after an eight-months pregnant woman was hit and killed by a vehicle involved in a two-vehicle crash.

Shortly after 8pm on Friday, emergency services responded to reports that a pedestrian had been hit by the vehicle at the entrance of a car park on George Street, Hornsby, in Sydney’s north west.

NSW Ambulance paramedics treated the woman at the scene before she was taken to Westmead Hospital in a critical and unstable condition. Both she and her baby subsequently died of their injuries.

The 19-year-old male driver of a white BMW and a 48-year-old male driver of a silver Kia Carnival station wagon were uninjured.

Both drivers were taken to Hornsby Hospital for mandatory testing.

No other occupants were in the vehicles.

Officers from Ku-Ring-Gai Police Area Command established a crime scene that was examined by officers from the Crash Investigation Unit.

The 19-year-old man was arrested at 12.45am on Saturday at a home in Wahroonga, and taken to Hornsby Police Station where inquiries are continuing.

Anyone with information about the crash – or was in the area at the time with any available dashcam/mobile phone footage – is urged to contact Hornsby Police Station or Crime Stoppers.

—AAP