Albion Park teenager Casey-lee Hull has died as a result of an accident in Shellharbour on Thursday.
Police have appealed for public for information to help investigations.
According to police several cars were travelling north on Boollwarroo Parade about 7.45pm. The vehicles included a Ford Falcon XR6 driven by a 22-year-old Warilla man, who was being followed by a 17-year-old Albion Park girl who was driving a black Suzuki Swift.
Police are investigating reports they were street racing.
It appears the teenager lost control of the Suzuki as she tried to negotiate a left hand bend. The car started to rotate and mounted the western kerb before striking a large tree.
The driver of the Falcon has spoken to police and is assisting with inquiries.
Emergency services were called to the area and the girl was eventually released from the car. She was treated at the scene by Ambulance Paramedics and flown to St George Hospital for immediate surgery.
The teenager died as a result of her injuries on Saturday. A report is being prepared for the coroner.
Officers attached to the South Coast Crash Investigation Unit attended and continue with their inquiries.
Police are urging anyone with information about this incident to call Crime Stoppers on 1800 333 000 or use the Crime Stoppers online reporting page: https://www1.police.nsw.gov.au/. Information you provide will be treated in the strictest of confidence.