Friends of 17-year-old Australian music fan Gemma Thoms, who died from a drug overdose at Perth's Big Day Out, have poured out their grief on social networking site Facebook.

Gemma died in hospital on Sunday night after passing out during the music festival on Sunday.

Witnesses said she took several ecstasy tablets before entering the festival's gates after she spotted police searching people for drugs.

She passed out soon after in 36 degree heat and was rushed to Sir Charles Gairdner Hospital, where she was pronounced dead overnight.

A group set up to mourn the young apprentice hairdresser, named BDO 09 Tragedy - R.I.P Gemma Thoms, has already attracted some heartfelt postings.

"This beautiful girl made one mistake that cost her her life," the group's administrator Deanne J Prus writes in an introduction.

"I don't believe everyone that overdoses are drug addicts & I'm sure her friends & family will confirm that this sweet girl was nothing like that.

"This is a group to remember Gemma & leave your kind words for her family & remember her."

Friend Bec Doolan's post epitomised the shock felt at Gemma's tragic death. "Holy snap! 3 tablets at a time *shocked*. WHY?! RIP Sweetie xxoo."

Fellow poster Kirsy Simpson echoed the grief. "So sad, there was no need for her to go this way!!!"

The group has also attracted people who didn't know Gemma, but were no less moved by her tragic death.

"I don't know this girl from a bar of soap but this has really upset me," Tim Philp posted.

He used the occasion to lash out at the WA Police for their involvement in the death. The police launched a major drug surveillance operation at the Big Day Out and arrested dozens for drug possession and other offences.

"The WA police need to take some of the responsibility for the death of the girl at the perth BDO," Tim writes.

"Nobody forced her to take the pills, but to not see this coming is pure ignorance. Busting someone with 5 pills at a concert does NOTHING to contribute to the wellbeing and safety of society.

"If the NSW and Vic Police want to put otherwise law abiding citizens thru this crap so be it. It made me proud that Perth cops left the heavy handed approach to recreational drug users to their eastern state counterparts.

"All this appraoch (sic) has acheived (sic) is the tragic death of a young girl and done absolutely nothing to make perth a safer place."