A 15-year-old boy has died after falling ill at a rave in which seven other people were also sent to hospital.
Scotland Yard said the cause of death has still to be confirmed and a post-mortem examination is being arranged.
The incident happened at a disused sorting office in Cherry Orchard Road, Croydon, in the early hours of June 15. The boy was taken from the venue by ambulance to hospital, where he died today.
A 19-year-old man, who also become ill at the same event, is still in hospital in a stable condition.
Scotland Yard said it is aware of six other people who were taken to hospital with injuries. All six have been discharged from hospital.
The rave was spotted by officers on routine patrol who saw "large numbers of people inside, outside and heading towards" the disused building where music was being played on Saturday at around 9.40pm.
Violence broke out after police tried to clamp down on the rave by trying to stop more revellers from getting close to the building. More police were called in and cordons were put in place.
Scotland Yard said that "a number of people in the crowd became violent, and missiles were thrown at police officers. The window of a police vehicle was also smashed."
Officers continued to surround the venue until they raided it on Sunday at about 8.30am.
In total 14 people were arrested in connection with the event for a range of offences including drugs offences, violent disorder and money laundering.
Two men have been charged with violent disorder and drugs offences and a 47-year-old man along with a 30-year-old man were given adult cautions for possession of class A drugs.
Another three men were arrested on suspicion of money laundering, a 17-year-old boy was arrested on suspicion of violent disorder and a 22-year-old man was arrested on suspicion of criminal damage. All five have been bailed pending further inquiries.
Scotland Yard said another five men are still in custody after being arrested today for handling stolen goods and criminal damage offences in connection with the investigation.