Emergency services were called to the city’s Move nightclub in the UK after midnight on Saturday night after the alarm went off.
Authorities said the drug involved is believed to be ecstasy, or LSD, and was taken in pill form.
The girl was taken to the Royal Devon and Exeter Hospital before she died.
Police said several teenagers were thought to have taken the tablets containing unknown substances.
The girl and her companions had enjoyed an evening between 16 and 18 at the disco.
A Move spokesperson told Metro.co.uk: “Following the tragic news from the Devon & Cornwall police this morning, we would like to offer our deepest condolences to the family and friends of the person involved. We are devastated by this awful tragedy. We have run the 16-18 year old nights for over 6 years to create a positive space around music for people of this age-group to express themselves and to enjoy music with friends. As a mark of respect Move nightclub will be closed until further notice.”
A 16-year-old boy from the Exmouth area was arrested on suspicion of being involved in the supply of a class A drug and detained for questioning.
Detective Chief Inspector Lee Nattrass said: “We have identified several teenagers already who reported that they had taken drugs, but we would urge anyone else who has felt unwell as a result to seek medical help and to contact us,” reports Metro.
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