Two men remain in a critical condition in hospital after consuming a potentially toxic substance at a house party in Waterford.
A third man who was being treated in intensive care has improved and is now in a stable condition, while a fourth man has been discharged.
It is understood that 15 people fell ill after attending the 21st Birthday party at a house in Ballybeg Square in Waterford last night.
Gardaí are examining a white substance which was found this morning at the house.
They have arrested a man in connection with the incident in Ballybeg Square.
One man, aged 25, was arrested in Waterford City this morning.
Gardaí and the HSE are encouraging any member of the public that may have been at the house party to present themselves at the Emergency Department in Waterford Regional Hospital or to their local GP if they are suffering from nausea or rapid heartbeat.
