TUESDAY UPDATE:
Tributes have continued to flow for Oyster Bay woman Sylvia Choi, 25, who died from a suspected drug overdose during the Stereosonic music festival on Saturday.
Among them, was one from her employer - Blooms The Chemist, Miranda, where Ms Choi worked as a pharmacist for the past three years.
In a statement released by the company, chief executive officer Phil Smith said staff were saddened by the news.
‘‘One of our bright, well-respected and highly professional pharmacists lost her life,’’ he said.
‘‘Our tight-knit Blooms The Chemist community has received the news of her passing with disbelief and is struggling to come to terms with the loss of a much-loved member of our team.
‘‘We extend our deepest condolences to Ms Choi’s family and ask the broader community to respect their privacy during this difficult time.’’
He said the tragedy illustrated the importance of not taking prohibited drugs.
‘‘There is no safe way to take prohibited drugs, and what has happened to Sylvia, can happen to anyone taking prohibited substances,’’ he said.
Monday story: Police have warned drug-taking festivalgoers that they are playing "Russian roulette with your life" after a woman died and another was placed in an induced coma following drug overdoses at Saturday's Stereosonic music festival.
A woman, 25, from Oyster Bay died after suffering a cardiac arrest believed to be caused by a drug overdose.
The woman, reported to be Sylvia Choi, fell ill at about 5.15pm and was taken to Concord Hospital where medical staff attempted to revive her. She was pronounced dead about 9pm.
Assistant Commissioner Frank Mennilli said investigators hoped a post-mortem examination, to be carried out on Sunday afternoon or Monday, would shed light on the type of substance or substances the woman took.
"We won't know the full result of the impact and cause of death of this until the autopsy has been conducted," he said, declining to comment on speculation she had taken ecstasy.
He said the woman's death was the latest in a string of incidents linked to music festivals, including the death of 19-year-old Georgina Bartter at Harbourlife just over 12 months ago.
"The mentality of drug culture and music festivals - we've got to change it," he said.
"There's no such thing as safe drugs. There's no such thing as saying you know you can take the drugs and you will be safe. You're playing Russian roulette with your life. You don't know what you're putting into your system."
The second woman, a 22-year-old tourist from Britain, has made a satisfactory recovery, he said. She has since been discharged from Westmead Hospital.
Mr Mennilli said there was no indication the women were known to each other.
A further nine people were taken to hospital following suspected drug overdoses. All have been released or discharged.
More than 120 people were treated from the effects of drugs during the festival at Sydney Olympic Park, and 69 people were charged with possessing and supplying drugs. A further 23 were issued with cannabis cautions.
At the same event last year, 221 attendees were charged - although 81,000 had attended, compared with closer to 50,000 this year.
Mr Mennilli said the "the situation could have been a lot worse" if not for the presence of more than 400 police officers and 60 medical staff spread across the precinct.
But he said it was alarming and disappointing that many revellers continued to ignore messages about the dangers of recreational drug taking.
"It's extremely frustrating. We've been working hand-in-hand with the organisers and promoters and venues to put out numerous messages to try and warn people about the effect of drugs but unfortunately the message does not seem to get through to some people."
The event's organisers, Totem Onelove, used social media to express "our deepest condolences to the friends and family of the patron who tragically passed away on Saturday night at Sydney Stereosonic".
"As it is a matter with the NSW Police and coroner we cannot make any further statements or comment," the company's post said.
A major police operation – involving officers from South West Metropolitan Region, the Dog Unit, Mounted Unit, Public Order and Riot Squad, Traffic and Highway Patrol, and Police Transport Command – was focused on the precinct for a variety of events in numbers thought to be the biggest seen since the Sydney Olympics in 2000.
One man who allegedly drilled a hole in a building to try to stash drugs there and another found with 95 tablets were charged last week.
"That's not personal use - that was there to sell," Mr Mennilli said.
He said drug manufacturers, dealers and suppliers "don't care" about the potential deadly effects on drug users.
"They're there to make money out of other's people misery. They make these tablets and drugs in the backyard, they put impurities in it," he said.
"Don't take the drugs, there's better ways of enjoying life, there's better ways of enjoying festivals. You put these things your body, you don't know how you're going to react.
"I can honestly tell you that if I had more police dogs and more police, it'd just result in more people being arrested," he said.
Facebook tributes to Ms Choi:
Aimée Louise: I went to school with Sylvia. I cannot comprehend this. She was amazing and so smart and talented and I am in utter shock. Rest In Peace Sylvo.
Bec Herbert: I am in shock! Poor Sylvia. My heart is heavy. Goodbye my high school friend, you’ll be dearly missed.
Minh-Thu Calzone: I studied pharmacy with Sylvia. She was fun, lively, intelligent.