Emergency services were called to Arundel Gate shortly before 1:50pm this afternoon (Sunday, October 6), following reports that a 40-year-old man had been stabbed twice, once in the back and once in the leg.
A 17-year-old man was arrested on suspicion of attempted murder and the victim was taken to hospital, but has since been released.
Eyewitnesses said four emergency services vehicles attended the scene including a police car and riot van, and an ambulance and ambulance responder vehicle.
Members of the public are said to have held the alleged attacker down until police arrived, while others helped the driver.
Bus company First confirmed one of their drivers had been injured and thanked those who helped him.
And eyewitnesses have also spoken of their distress at seeing what happened take place in broad daylight on a Sunday afternoon in Sheffield city centre.
Police are now appealing for information about the incident and say anyone who saw what happened should call South Yorkshire Police on 101 quoting incident number 481 of 10 October 2019.
Alternatively, people can call Crimestoppers, anonymously, on 0800 555111.