Police were called out to the incident in Staniforth Road, Darnall, at about 8.45pm on Friday evening.
The force said officers including police dog handlers had to disperse a group of people.
They were responding to reports that a 17-year-old boy suffered serious injuries to his leg.
He was taken to hospital.
Stagecoach Yorkshire tweeted that this cause temporary disruption for bus services.
A resident shared CCTV footage of two motorbikes colliding reportedly at the scene.
However, police said enquiries are ongoing to ascertain how the boy suffered his injuries.
Anyone with information is asked to call police on 101 quoting incident number 1118 of 17 June 2022.