Last Friday’s Trance Energy dance party at the Calder Park Thunderdome was marred by 26 drug overdoses, with four of those in a critical condition before later being released from hospital.

Some have argued the lack of police presence at the event was a contributing factor to the large number of overdoses, with no police sniffer dogs attending the all-day event.

The 26 overdoses are believed to be caused by the drug GHB, or gamma-hydroxybutyrate. Overdose symptoms associated with the drug include patients falling unconscious, difficulty breathing, dehydration, vomiting and fitting.

Trance Energy spokeswoman Erin Jameson said those involved with the event were frustrated by the actions of some of those who attended.

These terrible incidents on the Melbourne leg of the Trance Energy national tour has shocked the event’s organisers, who worked closely with police and safety authorities to comply with guidelines for the safest possible environment, she said in a statement released today.

All involved in Trance Energy share the Victoria Police Department’s anger and frustration that so many people are ignoring the dangers of GHB, when other Trance Energy events around the world have not had these issues.

Police arrived and closed the Calder Park event at around 10.30pm, half an hour before it was due to finish. Trance Energy events in other states over the Easter weekend did not encounter the same problems, with no drug-related illnesses reported at either the Sydney or Perth events.