Party-goers at a Sydney dance festival where a teenager died of an overdose played a dangerous game to see who could take the most pills, police believe.
A 19-year-old man from western Sydney collapsed at the State of Trance festival at Olympic Park on Saturday night after taking ecstasy.
He died in hospital and investigators are trying to work out whether he was playing the game.
Police believe the teenager had taken an "excessive number of pills".
Another man, a 20-year-old from Arncliffe, is on life support in hospital after also overdosing at the festival.
It is understood his parents did not know he was at the dance party.
Four other men were hospitalised after the weekend event in similar circumstances but they have since been discharged.
Police heard from people at the dance party that some revellers had turned their drug taking into a competition.
Assistant Commissioner Frank Mennilli said the game was idiotic.
"These people are gambling with their lives," he told reporters on Monday.
"It's absolute stupidity. Really there is no word for it."
Forty people were arrested at the festival, including one man who allegedly had 130 pills on him and another who was allegedly carrying 98.
The dance party ran from 10pm on Saturday until 5am on Sunday and attracted a line-up of international DJs.
Police are getting ready to boost their presence at two upcoming dance festivals, including Future Music and Soundwave.