Two men have been arrested following the death of a man who was stabbed in south-east London.
The 26-year-old victim died on Friday from wounds to his upper body, thought to have been sustained during a dispute in Peckham Rye.
On Monday, a 22-year-old man was held on suspicion of murder and a 28-year-old was arrested on suspicion of assisting an offender.
The Met has appealed for any footage of the fight to be passed to the force.
Video and pictures were posted online showing four police cars responding to the aftermath as people looked on in the street.
Det Ch Insp Dave Whellams said: "We believe the victim was involved in an altercation with another person prior to being stabbed. The incident drew a large crowd of onlookers and a number of members of the public were filming the incident on their phones.
"I am appealing directly to any witnesses - and in particular any of those people who have recorded footage - to contact police as soon as possible."
A post-mortem examination of the dead man established he was stabbed in the chest and arm.
His next of kin has been informed, but formal identification has not yet taken police.
He is the latest victim in a series of fatal stabbings in London in the past week.
Also on Friday, Archie Sheppard, 48, from Neasden, was found stabbed to death on the top deck of a bus near Marylebone station.
John Doherty, 38, from Fulham, has been charged with murder and two counts of possession of an offensive weapon.