A 19-year-old woman and a 22-year-old man are in critical condition in hospital after suffering suspected MDMA overdoses while attending St Helens’ Reminisce Festival.
The event organisers put out a warning that “bad” blue diamond pills on Saturday during the festival, encouraging anyone who had taken them or knows anyone who has taken them to seek help from stewards and onsite medical centres.
Police said a number of other people who went to the one-day Merseyside festival have also been taken to hospital with suspected overdoses.
The event promoter Lee Butler said: "I'm absolutely gutted to hear this news.
"Having children exactly the same age I cant stop thinking about them. I'm just praying they both pull through."
The festival organisers have said they are working alongside the police investigating the incidents.
Detective Inspector Paul Grounds, of Merseyside Police, said: "I want to reassure those affected that we are doing everything possible to identify exactly what substance or substances have resulted in these severe reactions, working alongside the health service.
"We initially believe that ecstasy tablets were taken by some of those in hospital but this is all subject to further enquiries.
"I would urge anyone else who has had an adverse reaction to any substance to make themselves known to medical services as soon as possible.
"Likewise, if you are still in possession of any drugs from the event, please do not take them under any circumstances but let us know and we will recover them for further enquiries to be made."
Patrick Hinton is Mixmag's Digital Staff Writer, follow him on Twitter