Metropolitan Police Service
The killing is the latest in a wave of knife crime which has engulfed the capital this year.
"Met Police go full Grand Theft Auto."
The Met Police have released a CCTV image of the man.
The teenager was fatally injured in Tulse Hill, South London.
Men aged 19 to 55 handed themselves in and are in custody.
One person has been arrested.
He has been bailed and women are urged to remain alert.
The party itself is not under investigation.
It relates to incidents at a number of hospitals, police say.