One man suffered minor injuries, South Yorkshire Police said.
Officers were called at around 8.20am on Saturday after reports that a man had been stabbed.
The force said: “An investigation is now under way and in its early stages to establish whether this is an isolated incident and whether the individual acted alone.”
There is a high-visibility police presence in the town centre, the force added.
A representative for Travel South Yorkshire said that the station was open as normal and there were no reported delays to trains or coaches.