Three of the people stabbed at the show are reported to be seriously injured, one critically so.
Managing director of concert promoters MCD Denis Desmond said: "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."
He added: "Despite our best efforts - with security and gardaí [police] personnel levels well in excess of the required numbers for a licensed event of this size - there is only so much one can do to combat anti-social behaviour."
CCTV footage from the event has been given to the police. 30 people were arrested and charged with various drugs, assault and public order offences before being bailed.
Meanwhile, a man in his early 20s from Clonsillla in Dublin who died of a suspected drug overdose at the show has also been identified.