Shortly after 2am, a police patrol discovered the scene of a crash between a motorcycle and a Mazda 3 hatchback at the intersection of Main Road and Lowry Street, Cardiff.
Police immediately stopped and rendered first aid to the riders of the bike before paramedics arrived.
The rider and the pillion passenger, both 16-year-old boys, were taken to John Hunter Hospital in a serious but stable condition. Both were wearing helmets at the time of the crash.
The driver of the Mazda, a 52-year-old man, was uninjured.
He was taken to hospital for mandatory testing.
As an investigation into the crash continues, police allege they have established the bike was reported stolen from Edgeworth on May 11 this year.
It had not been involved in a pursuit prior to the crash.
Anybody with information or any dashcam or mobile phone footage is urged to contact Belmont Police or Crime Stoppers on 1800 333 000.
