A man in his early twenties died last night after becoming ill at a concert in Dublin's Phoenix Park in which seven people were also stabbed.
The man was attending the Swedish House Mafia concert in Dublin.
He was treated by medical staff at the site before being taken to Blanchardstown Hospital where he was pronounced dead.
Gardai have not been able to identify the man and are asking family and friends to check that loved ones have arrived home safely from the event.
Anyone who has concerns regarding a friend or relative should contact Blanchardstown Garda Station on 01 666 7000.
Separately, a man has been arrested after a number of stabbing incidents at the same concert.
All told, seven men were wounded and brought to hospitals around the city for treatment.
All but one of the men were subsequently discharged. One man is still being treated at Connolly Memorial Hospital in Blanchardstown.
A 23 year old man at the scene and he is being questioned at Blachardstown Garda Station, under section 4 of the Criminal Justice Act.
More than 45,000 fans attended the concert in the Phoenix Park, which also featured acts including Snoop Dog and Tinie Timpa.
Gardaí have appealed to witnesses to come forward.
MCD's Dennis Desmond said the promoter was "very disappointed that an individual or very small number of individuals engaged in anti-social behaviour, attempting to spoil the enjoyment of others".
He said it was "not reflective of the vast majority of the 45,000 fans who were extremely well behaved and should be congratulated".
In a statement released this afternoon he described public safety as "our number one priority and we actively engage in detailed planning in advance to ensure this.
Ticket holders entering the site were subject to a search permissible by law. Every precaution as far as possible was taken to ensure the safety and security of the audience at all times. All CCTV footage captured from the area has been supplied to the Gardai.”
