Police investigating the death of a 15-year-old girl believed to have taken MDMA have named her as Leah Heyes.
She died in hospital after collapsing in a car park on Saturday night.
North Yorkshire Police said it had arrested a teenage boy on suspicion of drugs offences as it issued a warning about MDMA to drug users.
The teenager died in Northallerton, North Yorkshire, at about 9.30pm on Saturday night.
A force spokesman said: “Police are now in a position to name the 15-year-old girl who died in hospital after collapsing in the Applegarth car park, in Northallerton, on the night of Saturday 11 May.
“Her name is Leah Heyes from Northallerton.”
He continued: “We believe that Leah had taken the drug MDMA - also known as ecstasy or a ‘bomb’ - prior to collapsing and we reiterate our warning to anyone who uses drugs of the potential consequences.
“At this stage, one teenage boy has been arrested on suspicion of being concerned in the supply of class A drugs.
“However, officers have not ruled out making further arrests as the investigation continues.”
Police said the boy who is being questioned is 17 years old.
The force said officers are continuing to investigate to determine the circumstances surrounding Leah’s death on Saturday night.
A post-mortem examination will be carried out to determine the cause of her death.
On Sunday, Detective Inspector Jon Sygrove advised anyone who had bought MDMA recently to be cautious about taking it.
He urged anyone who had taken the drug and was feeling unwell to seek medical help immediately.
Police have asked anyone who was in the area at the time, or has any information about the events on Saturday night, to come forward if they have not already done so.
Anyone with information is asked to call North Yorkshire Police on 101, select option two and ask for Northallerton CID, or contact Crimestoppers anonymously on 0800 555111.