A man has been assaulted on a Southeastern train at Lower Sydenham.
British Transport Police (BTP) has reported a male in his 20s was "cut" on a morning service running from Hayes to Charing Cross.
The rail operator said "the train has become a crime scene" and will be taken to the depo for investigation.
Passengers on the train had said someone may have been stabbed in the incident.
User '@ELemoine' said: "Little stabbing in train lower Sydenham. Late for meeting as many others".
While '@Bchagtai' commented: "...at lower Sydenham station, someone got stabbed in the leg (so people say randomly) by someone who got on the train stabbed and got off".
And '@capiegirl' tweeted: "Just been told to get off train at New Beckenham due to crime scene at lower sydenham #marooned".
British Transport Police and London Ambulance Service attended.
A BTP spokesman said: “BTP officers were called to Lower Sydenham station in south-east London on Thursday June 5 following a report that a man had been assaulted.
“The incident, which was reported to BTP at 9.54am, took place on the 9.53am Sydenham to Charing Cross service.
“Colleagues from the Metropolitan Police and medics from the London Ambulance Service also attended.
“A man in his 20s was treated at the scene for a cut to his leg before being taken to a local hospital.
“Enquiries into the incident are ongoing.”
Southeastern has reported disruptions to the line, informing passengers "trains may be cancelled, delayed or revised".
Replacement travel arrangements are in place.
More to come.
Were you on the train? Email firstname.lastname@example.org or tweet @joshbythesea