The window of a police van was smashed at the rave, which took place in a disused post office in East Croydon.
As The Independent report, the party, which took place in a disused post office on Cherry Orchard Road, was attended by around 1,300 people.
Met Police say a patrol noticed people heading to the party at about 9:40 PM on June 14th. They later cordoned off the area to prevent "dangerously large numbers of people" from entering. It's estimated that at one point about 300 people were inside the building, with a further 1,000 outside.
Nine arrests were made: two for violent disorder, and seven for drug offences and money laundering. A BBC news piece says further arrests may happen "as a result of evidence gathered during the police operation overnight and at the scene." Some missiles were thrown at police, and the window of a police van was smashed.
Croydon Central MP Gavin Barwell told the BBC: "It is clearly unacceptable to have a situation where people are allowed to occupy a building, disrupt the whole public transport system and keep a lot of the people that live in the area up all night. I'm all for people having a good time but it has to be in a safe environment."
Photo credit: The Independent