PARAMEDICS have declared a major incident at the the Odyssey Arena in east Belfast.
The Ambulance Service says crews have dealt with 60 young people attending the Hardwell dance concert at the venue became ill.
It is understood at least five have been taken to hospital while attending the gig.
They are being treated for the effects of drugs and alcohol.
According to sources, paramedic crews called in a doctor and a number of ambulances to deal with the emergency.
The Ulster Hospital and the Royal Victoria Hospital have now put extra staff on standby to help cope with the situation.
Former Sinn Fein Lord Mayor of Belfast Niall O’Donnghaile tweeted: “From what I understand the event is carrying on inside and in terms of the overall number attending those affected are still small.”