The 16-year-old boy murdered at Croydon Arena early this morning has been named locally as Wesley Sterling.
The teenager was reportedly a former student at St Mary's High.
He was stabbed to death at a 16th birthday party just after midnight.
A 15-year-old boy has been arrested on suspicion of murder and possession of an offensive weapon. He remains in custody at a south London police station.
Police do not know what Wesley was doing in the area at that time of night as it is not thought he was a guest at the birthday party.
A spokesman said: "Police are appealing for information about the stabbing and an earlier incident at the same venue.
"At approximately 11pm Saturday April 17 a group of six to eight males tried to gate crash the same venue which was holding a 16th birthday celebration.
"At this early stage is believed the victim was not a guest at the party and it is unclear what he was doing in the area."
Police and ambulance crews were called after a disturbance the scene on Albert Road, South Norwood at 12.18am, where they found the 16-year-old, who had been stabbed in the chest, in a walkway near the club.
Detective Inspector Alison Hepworth investigating from HSCC said: "We know there were many guests at the party and would appeal to them to come forward with information on what happened."
Hundreds of friends have joined tribute pages set up on facebook to the young man.
Henry Timson said: "I will really miss Wesley aka Solemn he was a good friend, funny guy, he had plans of becoming a music artist and everyone has love for him. Gone but not forgotten."
Mark Laing wrote: "Fam I never in my life thought this would be you, Don, I swear down I'm cryin now. I love you fam. Dis is madness."
His friends say he was due to turn 17 in May.
Anyone with any information is asked to call the incident room in Sutton 0208 721 4005 or Crimestoppers anonymously on 0800 555 111.
Do you know what happened? Contact the newsdesk on 07825715315.
Leave your tributes to Wesley using the comment feature below.
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