Police are searching for a motorcycle rider involved in a two-vehicle crash in Kogarah earlier today.
About 5am, emergency services were called to the Princes Highway, near Gray Street, Kogarah, after reports a Suzuki DRZ400 and Hyundai Excel collided.
Police have been told the rider fled the scene prior to their arrival.
The pillion passenger, a 15-year-old boy, was treated at the scene for head injuries, before being taken to St George Hospital. He has since been transferred to the Children's Hospital at Westmead in a serious condition.
The driver, a 56-year-old man, was uninjured.
Officers from St George Police Area Command attended and commenced a search of the surrounding area, with assistance from the Dog Unit, however, the rider was not located.
Inquiries have revealed the Suzuki was stolen from Tamarama.
Anyone with information about the crash - or anyone with dashcam vision - is urged to come forward.
Inquiries are continuing.
Anyone with information about this incident is urged to contact Crime Stoppers: 1800 333 000 or https://nsw.crimestoppers.com.au. Information is treated in strict confidence. The public is reminded not to report crime via NSW Police social media pages.