Three men are critically ill in hospital in Waterford after a suspected bad batch of drugs were allegedly taken at a birthday party.
Fourteen people in total have received emergency medical treatment.
In a statement, the Health Service Executive confirmed its emergency services attended an incident in the Ballybeg area of Waterford city early this morning following requests for assistance.
Five ambulances and a single response unit were in attendance, in addition to the chief ambulance officer, the HSE said.
"Fourteen people subsequently attended the emergency department at Waterford Regional Hospital. As a result of the attendances, a total of three persons were admitted for further treatment.
"Three male patients remain critical at Waterford Regional Hospital," the HSE said.
"In accordance with advice being imparted by An Gárda Síochána, the HSE is encouraging any member of the public that may have been at the house party in question to present themselves at the emergency department in Waterford Regional Hospital or to their local GP - particularly if they are suffering from nausea or rapid heartbeat.
It is understood the people all fell ill after attending the 21st birthday party last night.
Gardaí in the city are reportedly examining a white substance which was found this morning at the house. However, a Garda spokesman could not confirm this.
Gardaí also urged all those who attended the 21st celebration in Ballybeg Square who feel "nauseous or unwell" to seek immediate medical attention.
"Any person who needs to contact Waterford Regional Hospital should also contact Waterford Garda station," said a garda spokeswoman.
"The gardaí urgently need to speak with any person who attended this party at any time last night."
Additional reporting: PA