A man killed in a multiple stabbing attack on Halloween night has been named as 22-year-old Scott Kouebitra, police said
The victim, from Sutton in south west London, was treated by paramedics but died at the scene in Gloucester Road, Croydon at around 8pm on Monday.
Three other men, aged 21, 27 and 22, also suffered stab wounds and continue to be treated at hospital but their injuries are not thought to be life-threatening, the Metropolitan Police said.
Police think the men were known to each other and are urging witnesses to get in touch.
However, many onlookers had their faces covered as they ran away from the scene of the attack.
Detective Chief Inspector Sam Price said: "We now know that there were a large number of people in and around St George's Field Park on the evening of the fatal attack and the other stabbings.
"If you were there and saw anything that could assist investigators I would urge you to get in touch.
"There has been a lot of speculation concerning the motive for this attack and whether this was a Halloween related ASB incident that got out of control.
"Whilst we are retaining an open mind, we believe that all the victims are known to each other and as a result early indications suggest that this was not a random attack."
No arrests have yet been made in connection with the attack, the Met added.
Detectives from the homicide and major crime command continue to investigate.
Ms Price added: "Many of the group we are seeking to trace did wear balaclavas and masks as they fled the scene.
"A young man has had his life taken away - your information could be vital to piecing together the events that unfolded that evening."
A post-mortem examination was held on Wednesday November 2 at Croydon Mortuary.
Anyone with information is asked to contact the incident room on 020 8721 4054 or via 101.