Emergency services were called to an area off Caerphilly Mountain Road in the early hours of yesterday morning, Sunday 18th June 2017 following concerns for the health of a 15 year old girl.
Shortly after paramedics and police officers attended the scene, the girl, who was from the Caerphilly area sadly passed away.
The circumstances surrounding her death are not yet known and an investigation is ongoing.
Her family are being supported by specialist officers at this time.
During the incident four people were taken to hospital for checks following concerns for their health.
The four were arrested on suspicion of being concerned in the supply of drugs, they have since been released pending further investigation.
Detective Chief Inspector Nicola Brain, who is leading on the investigation said: "At this time enquiries are ongoing and the investigation in this young girl's death are still in the early stages.
During our work we will be looking into whether any substances have been a contributing factor into this incident however; this is just one of our lines of enquiry at this time.
A post mortem examination will be carried out to determine the exact cause of death. Our thoughts are with her family and friends at this time.
I'd like to appeal to anyone who can assist with our investigation, to please come forward and call us on 101 quoting log number 16 18/06/17 or Crimestoppers anonymously on 0800 555 111.'