A man has died and another is in hospital following a stabbing at a Tube station.
Police were called to Elephant and Castle station at about 23:30 BST on Sunday and found two men with stab wounds in a street nearby.
A 24-year-old man died on Monday and a 25-year-old is in a serious condition.
British Transport Police said it was "a shocking act of violence" and two men had been arrested on suspicion of violent disorder.
Officers said they believed the stabbing happened during a fight between two groups of men and added they were treating the death as murder.
Keylin Tejeda, 32, from Elephant and Castle, said one of the victims was a regular customer at her pattie shop El Monte.
"I was coming from a restaurant with my partner and when we were passing by we saw him lying down.
"I could see who he was, I saw him. The ambulance were operating on him on the floor," she said.
Det Ch Insp Sam Blackburn said: "This was a shocking act of violence and we are working tirelessly to identify and trace those responsible.
"While the investigation is still at an early stage, at this time we believe there was an altercation between two groups of men inside the Underground station and it is here the victims sustained their injuries before making their way on to the street."
London Mayor Sadiq Khan called the death "a senseless loss of a young life" and urged witnesses to contact police or Crimestoppers.
The death brings the number of homicides in the capital to a total of 92 so far this year.