Investigations are continuing into the deaths of two people at the Mutiny Festival in Portsmouth.
An 18-year-old woman and a 20-year-old man died after falling ill on Saturday evening
The deaths are being treated as separate incidents and are not being treated as suspicious but Hampshire Constabulary are investigating the circumstances.
The festival has cancelled the second day of the event, which was to be headlined by Craig David and Sean Paul, after warning of a "dangerous high strength or bad batch substance on site".
Organisers posted this message on their website shortly after 9 o'clock this morning:
The announcement, which organisers said was a "safety precaution", prompted demands for refunds from disappointed customers on social media.
Police were first alerted to the woman falling ill at the site on Saturday evening and the man was found collapsed around 20 minutes later.
Both were taken to the Queen Alexandra Hospital where they later died.
The organisers also urged customers to "responsibly dispose" of any substances.
Police have appealed for anyone with information to come forward.
The force said: "At 7.10pm on Saturday 26 May, we were informed that an 18-year-old woman had fallen ill at the festival site in King George V Playing Fields, Cosham.
"The woman was taken to Queen Alexandra Hospital where she later died.
"At 7.30pm, a 20-year-old man was found collapsed at the festival site. He was taken to Queen Alexandra Hospital where he later died.
"The deaths are being treated as separate incidents at this stage. They are not being treated as suspicious but inquiries are being made to determine the circumstances of what happened in each case."
The force said next-of-kin for both the woman and the man had been informed and were being supported by specialist officers.