Paramedics say it’s the highest number of overdoses seen at a music festival in recent times.

More than 20 people are reportedly in a critical condition after overdosing on GHB at Melbourne’s Electric Parade festival last night (February 18).

As Huffington Post Australia reports, 21 people were taken to hospital at Australia’s “biggest inner city electronic music festival,” while another seven people were treated after leaving the event and collapsing in parks and streets near to the Sidney Myer Music Bowl location. There are reports that the substance may have been a synthetic version of GHB.

Paramedics said it was the highest number of overdoses seen at a music festival in recent times, while Australia’s Mental Health Minister Martin Foley said: “This was a tragedy of the proportions that we have not seen when it comes to drug overdoses at these kind of events.”

Police arrested 40 people at the festival, including 33 men and seven women. “One man was charged and remanded overnight after quantities of ecstasy, cocaine, MDMA, LSD, ketamine and hash were located on him,” according to a police statement.

The mass overdose has sparked a national debate about the need to introduce on-site drug testing at similar events.

FACT has reached out to Electric Parade festival for comment.