First South Yorkshire said the collision near to the Northern General on Barnsley Road is affecting a number of services.
Its number 11, 32, 32A, 95 and 95A services have been diverted away from the crash scene.
The 11, 95 and 95A services are being diverted via Firth Park Road, missing Barnsley Road and Hucklow Road.
The 32 and 32A services are diverting along Hucklow Road, missing out the Northern General.