A teenager is in a life threatening condition in hospital after being thrown from a trial bike in Parson Cross.
The accident happened on Buchanan Road at around 12.30am yesterday between Collinson Road and Adlington Road.
Two 19-year-old men were on the 125cc bike when the rider is believed to have lost control while travelling towards an oncoming police car.
One of the men sustained life threatening injuries and is currently in a critical condition.
The second man sustained minor injuries and was arrested on suspicion of dangerous driving and theft of motor vehicle.
South Yorkshire Police’s professional standards department and the IPCC have been informed. Witnesses should call 101.