A 16-year-old boy has died and a police investigation is under way into whether he had taken an ecstasy tablet at Leeds Festival.
The teenager fell ill on Saturday at the music event and was taken to hospital, but he died on Sunday.
West Yorkshire Police said they are looking into whether he had taken a particular type of MDMA.
Police said the boy’s parents have been informed and officers believe this was an isolated incident.
Assistant Chief Constable Catherine Hankinson said: “Our thoughts are with the family of the boy who has died, and we have officers supporting them at this very difficult time.
“While the exact cause of his death is yet to be established, one line of inquiry is that he had taken a particular type of ecstasy (MDMA) tablet, which was described as a grey or black oblong shape.
“At this moment in time this is believed to be an isolated incident as we have not received any similar reports.
“Users of any drug which is not professionally prescribed can never be sure of their contents and the risks involved with taking the substance.
“Anyone who does feel ill after taking any substance should seek urgent medical attention.”
“We are continuing to conduct inquiries on site and are liaising closely with the event organisers.”
Anyone with information is asked to contact police or security on site, call 101, or visit the West Yorkshire Police website.
Those behind the festival said they are “working closely” with police to help with their investigation and that they “take all reports of incidents where drug use is suspected seriously”.
Melvin Benn, managing director of Festival Republic, said: “We are truly saddened about this tragedy and our sincerest thoughts are with the family at this time.
“We are working closely with West Yorkshire Police to assist with their investigation and take all reports of incidents where drug use is suspected seriously.
“The safety and wellbeing of all our festival goers is always our absolute priority and we remind all festival goers that there is no safe way to take prohibited drugs and there are no safe prohibited drugs.”
Saturday’s headliners at Leeds included rapper Dave, Little Simz and Megan Thee Stallion.