Police said George Verrier, 17, a trainee electrician, refused to go to a hospital after being injured early Sunday, the Daily Mirror reported. He was at a friend's house hours after the brawl when he was found dead.
The outdoor party Saturday night in the Bromley district in southwest London was attended by about 100 people, investigators said. It was hosted by the family of Madison Moran, a dance student at the London School for Performing Arts & Technology, also known as the BRIT School because it is supported by the British Record Industry Trust.
A 17-year-old was arrested on suspicion of murder, and police said they were looking for others involved.
Neighbors described the party as loud with guests spilling into the street.
"I am still trying to work out how last night was such a good party but ended with about 40 people having a full-blown punch-up," one of the teenage guests said in a tweet.
Detective Chief Inspector Diane Tudway asked anyone who was in the area or driving by early Sunday and saw anything of the brawl to talk to police.
The BRIT School in South London, which was founded in 1991, already has a list of well-known alumni including Adele and the late Amy Winehouse.
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