Police and paramedics were called just after 7 o’clock.
The station was closed off for a number of hours but has since reopened.
Enquiries into this incident are ongoing, and anyone who may have witnessed the incident or has information is asked to contact BTP by texting 61016 or by calling 0800 40 50 40, quoting reference 89 of 26 September.
T/Detective Superintendent Sam Blackburn said: “There is absolutely no place for violence on the railway network and detectives are working at pace to investigate the incident. The station will remain closed while our initial enquiries are carried out, and the public will see increased high-visibility patrols in the area and across the network to provide reassurance.”