A murder inquiry has been launched following the stabbing of a man on board a train in Surrey.
British Transport Police (BTP) said officers were called to Horsley station at 1.15pm on Friday to reports of an attack on the 12.58pm train service travelling between Guildford and London Waterloo stations.
Officers from Surrey Police and South East Coast Ambulance Service also attended the incident in which the victim suffered a “fatal stab wound”.
BTP said the injured man died at the scene of the “frightening” attack.
A number of police officers remain in the Clandon area and are attempting to identify and trace the man responsible for the assault.
No arrests have been made at present, police said.
Detective Superintendent Gary Richardson from BTP 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 whoever 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 inquiries continue.
“We would advise anyone in the local area who sees anyone they think may be the suspect to contact 999 immediately.”
Transport Secretary Chris Grayling tweeted: “The incident near Horsley is tragic, and our deepest sympathies are with the victim and their family. I urge anyone who witnessed what happened to contact @BTP and @SurreyPolice, by texting 61016 or calling 0800 40 50 40.”
One social media user who said they had been on the train praised the “incredible” response of the guards and driver in a tweet to South Western Railways.
They wrote: “I was on this train, how those guards and especially that train driver went into action was nothing short of incredible. Not sure if it’s appropriate to say thank you, but I do hope everyone is ok after today’s event.”
Matt Phelps, 35, who works at a business on Epsom Road in West Clandon, said police officers provided a description of the man they were hunting – a man with a beard and short hair, who was “not dressed for the weather” in a T-shirt and tracksuit bottoms, and strikingly bright white trainers.
He said: “There were also three helicopters circling overhead when we locked up and went home.
“It was a bit alarming when someone I worked with put two and two together and we realised who the police were looking for.
“You sometimes see the police helicopter going over or cars going past with sirens on but to think there was someone like that potentially hiding around the corner somewhere certainly made us want to pack up and go home quicker than usual.”
South Western Railway said the train line between Guildford and Effingham Junction stations towards London Waterloo is blocked while police deal with the incident.
Train services through these stations may be cancelled, delayed or revised, with the disruption expected to last until 9pm.
Services are not stopping at Clandon or Horsley in the Guildford direction.
Trains from Guildford towards Effingham Junction will be diverted through Woking.
Rail replacement buses are being provided and train tickets are being accepted on Southern Railway services between Dorking and Clapham Junction and some Stagecoach bus services.