A 20-year-old man has been arrested in Gloucestershire on suspicion of supplying controlled drugs and manslaughter following the sudden death of an 18-year-old man yesterday morning.
He remains in custody, along with an 18-year-old woman arrested in Bristol on the same charges.
A number of searches are currently being conducted by officers in connection to this investigation.
The teenager died yesterday at a party on Chobham Common, Surrey.
A post mortem was due to be carried out today. The teenager has not yet been formally identified.
Officers were informed of his death by the South East Coast Ambulance Service at around 10.15am yesterday.
The 18-year-old, who is from the Farnham area of Surrey, was at a party on Saturday night and took an unknown substance, potentially through an inhaler, prior to his death.
Following initial enquiries, it is believed that the substance involved may have been sold as 2C-I or 2C-E.
An urgent warning has been issued to recreational drug users who were at Saturday's event and took this drug to seek urgent medical attention if they start to feel unwell.
Temporary Superintendent Matt Goodridge said: "Our advice is to go to A&E immediately if you believe you took this drug and start to exhibit worrying symptoms. Similarly, if you think you have taken this drug elsewhere and start to feel unwell, our advice is to seek urgent medical attention.
"We have carried out extensive enquiries following the tragic death of this young man and the fact that we have already made two arrests demonstrates our commitment to tackling the use and supply of illegal drugs. The message is clear - drug dealing in any form will not be tolerated on the streets of Surrey.
"We also need the public's help in getting this potentially fatal drug off the streets of Surrey. Anyone with information about this substance or with any other information which could aid the ongoing investigation is asked to call Surrey Police on 101. If you have information but do not want to give your name you can pass details to independent charity Crimestoppers anonymously on 0800 555 111.”
Anyone who was at the event on Saturday night and has not already spoken to officers should contact Surrey Police on 101, quoting Operation Fox.