An 18-year old woman has died at the Tonnau festival at the Carreglwyd estate in Llanfaethlu.
Emergency services were called following reports of a medical emergency at around 1.45am on Saturday morning.
The young woman, who had been attending the event, was taken to hospital where she later died.
Her death is being treated as unexplained and the local coroner for North West Wales has been informed.
The remainder of the Tonnau festival, which was due to continue until Sunday evening, has now been cancelled while investigations into the death continue.
The event had been billed as a ''family-friendly tropical garden party'', featuring live music from international bands and DJs.
Earlier, an email sent to ticketholders asked for attendees to leave the site by midday on Sunday - with no further admissions being allowed.
In a statement on Saturday night, a spokesperson for the organisers said: "Everyone at Tonnau Festival is devastated to confirm that a festival attendee passed away in the early hours of Saturday morning following a severe medical emergency."
"Our thoughts and deepest condolences are with the attendee's family and friends during this incredibly difficult time."
"From the moment the attendee became unwell, our on-site welfare teams, security and emergency medical staff responded immediately."
"Paramedics and welfare personnel did everything they could to provide emergency care, but unfortunately, they died later in hospital."
Annoucing the decision to cancel the festival, the statement continued: "The safety and wellbeing of our audience is always our highest priority."
"Following this tragedy, and to allow emergency services and local authorities to conduct their necessary work, we made the decision to close the remainder of the festival and have asked people to vacate the site when it is safe to do so."
"We appreciate the understanding and co-operation of all our attendees, staff and volunteers during this incredibly difficult situation."
"Out of respect for the family's privacy, we will be making no further comment at this time. Our thoughts and hearts are with the family."
North Wales Police are urging the public to speculate the circumstances surrounding the death but they are appealing for anyone with information to come forward.
Detective Inspector Iolo Edwards said: “Our thoughts remain with the woman’s family and loved ones at this difficult time."
"We urge members of the public not to speculate on the circumstances of the death, and anybody with information that could assist our enquiries" should contact us via our website or by calling 101, quoting reference O110259."
Altenatively, you can use the live web chat on the North Wales Police website.


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