The Sydney Morning Herald this morning has reported that last night's Genesis Black Subculture party in Moore Park was closed down at 2am.
Police shut the event down after "a number of partygoers" were rushed to hospital suffering from suspected overdoses.
A police drug operation, involving the dog unit, had been conducted at the party from 7pm.
A spokesperson for the NSW police said that there was early concern about "the number of drug-affected patrons" at the event attended by 5,000 party-goers.
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However the party was only shut down at 2am, an hour before it was due to end, after paramedics treated four people for suspected drug overdoses.
Police report that it was not clear what type of drugs had been consumed by the people treated and would continue to investigate the incident. They believe there is evidence that "drugs were being supplied at the event".
Event organisers posted a statement following the closure: "We are as disappointed as you are with the early end to tonight's event but hope you can understand that it was out of our control!"