The boy who died after falling ill at rave in a disused sorting office has been named as 15-year-old Rio Andrew.
The schoolboy, of west London, died yesterday after being taken to hospital in the early hours of Sunday morning.
Friends paid tribute the "beautiful genuine smart young lad" in messages posted online.
One tweeted: "A million and one good memories, laughs and silly arguments to remember with my lil bro".
Another wrote: "If only I stopped you and advised you not to go to that rave you are such a beautiful genuine smart young lad," adding "may you rest in eternal peace sir because you of all people most definitely deserve it".
The teenager, a Chelsea fan, attended Holland Park School, in Kensington.
A post-morterm examination to establish the cause of his death has not yet been held and he has not yet been formally identified.
A 19-year-old man, taken ill at the same rave in Cherry Orchard Road, remains in hospital in a stable condition.
Did you know Rio? Call the newsdesk on 0208 722 6351 or email firstname.lastname@example.org