A train passenger died after being stabbed to death aboard a London-bound train from the home counties.
The man was knifed on the Guildford and Waterloo service just before 1pm today.
It is believed the man and his killer boarded the train at London Road, east of Guildford and the killer got off at Clandon.
The train pulled into Horsley station but despite the efforts of air ambulance doctors, paramedics and police officers was pronounced dead at the scene.
British Transport Police have now launched a murder investigation.
Detective Superintendent Gary Richardson from British Transport Police, said: “This was a shocking and violent attack which took place on-board a train in broad daylight.
“Officers from BTP are with the family and have deployed a specially trained family liaison officer to support them through this difficult time.
“We know that this was an incredibly frightening incident for passengers travelling on the train.
“We believe that the suspect and victim boarded the train at London Road at 1.01pm and we would encourage who was on this train to come forward regardless of whether or not they think they can help our investigation.
“We believe the suspect departed the train at Clandon station.
“Passengers and members of the public can expect to see an increased presence by BTP and Surrey Police officers at Horsley and Clandon as our enquiries continue.
“We would advise anyone in the local area who sees anyone they think maybe the suspect to contact 999 immediately.”
A spokesperson said: “Detectives at British Transport Police (BTP) have launched a murder enquiry following a serious incident on board a train between Guildford and Waterloo earlier today.
“At 1.15pm this afternoon officers from BTP, along with colleagues from Surrey Police and the South East Coast Ambulance Service, were called to Horsley station, after a report that a man had been stabbed on board the 12.58pm train service travelling between Guildford and London Waterloo.
“The victim suffered a fatal stab wound and despite the best efforts of officers and paramedics, he sadly died at the scene.
“A number of officers are now in the Clandon area, attempting to identify and trace the man responsible for this assault.
“No arrests have been made at present. ”
South Western Railway said: “Due to the police dealing with an incident between Guildford and Effingham Junction the line is blocked.
“Train services running through these stations may be cancelled, delayed or revised. Disruption is expected until 9pm.
“We have been informed that the police are dealing with an incident between Clandon and Horsley.
“Until the police have carried out their investigations the line between Guildford towards Effingham Junction is currently blocked.
“Services will not be stopping at Horsley and Clandon Stations.
“Trains from Guildford towards Effingham Junction will be diverted through Woking.”
By Tony Whitfield