Police have made an arrest after a man was stabbed to death in front of his teenage son on a train in Surrey.
The 51-year-old victim was stabbed multiple times after a three-minute altercation on board the 12:58 Guildford to London Waterloo service.
The suspect was detained at an address in the Farnham area at 6am this morning on suspicion of murder, along with a 27-year-old woman, who was arrested on suspicion of assisting an offender.
Police described the suspect as a a bearded black man in his 20s to 30s, approximately 6ft tall and of slim build.
Detective Chief Inspector Sam Blackburn, from the British Transport Police, said he was confident that this was not "a random assault".
"In the moments leading to the violent killing, both men appeared to be involved in an altercation lasting three minutes," he said.
"Nothing justified the extraordinary violence that followed and we are concentrating our efforts on the on-going investigation."
It is believed the two men were involved in a verbal discussion which moved from the carriage in which they boarded to another carriage, before escalating into a violent attack.
Police and paramedics were called to Horsley station following the attack. Image: Lizzie Roberts/PA
Police say the knifeman left the train at Clandon station and headed in the direction of Dedswell Drive.
A woman who lives locally reportedly told other villagers that she had spoken to a "very sweaty and nervous" man in a field near her home.
The son and other family of the victim are now being supported by specially trained family liaison officers.