Jessica Moore, 19, was enjoying her school “Debs ball” when she fell unwell overnight.
Her friends called an ambulance as paramedics raced to the scene at a hotel in Ballinasloe, County Galway in Ireland.
Jessica was then rushed to hospital where she was sadly pronounced dead in the early hours of this morning.
The Gardai has now launched an investigation into the death of the teenager from Loughrea, Co Galway.
A source said: “Jessica took ill sometime after 2am, she said to her friends that she wasn’t feeling well and then collapsed.
“Statements will be taken from other students at the event and anyone else that came in contact with Jessica.
“CCTV at the venue could also form part of the investigation.”
Jessica was a student at St Raphael’s College in Loughrea and on Monday the principal at the school, Paul Cafferky, paid a heart-rending tribute to her.
He said: “We are deeply shocked at the death of Jessica. Our immediate concerns are for her family and for our students and staff.
“I would say we are devastated obviously by the news. The girl (Jessica) was immensely talented, a very, very bright student.
“She was very mature and responsible, very sensible who came from a fantastic family and was admired and respected by everyone.”
A Gardai spokesman said: “Gardaí are investigating a sudden death incident involving a 19 year female that occurred in the early hours of Monday 12th August 2019 at a hotel in Ballinasloe, County Galway.
“After being informed the female felt unwell, an ambulance was called and she was taken to Portiuncula Hospital where she was later pronounced dead.
“The coroner has been notified and a post mortem is expected to take place on Tuesday 13th August 2019. Investigations are ongoing.”