A boy of 17 has been arrested in the Oxford area following the death of a 15-year-old girl who collapsed after reportedly taking a £3 pink ecstasy tablet.
Martha Fernback allegedly took what she believed to be an MDMA pill - commonly known as ecstasy - at a recreation ground in Oxford on Sunday.
The police and paramedics raced to Hinksey Park and gave Martha CPR in front of shocked members of the public after she had a reaction to the drug.
She was airlifted to hospital where, despite frantic attempts by doctors to save her life, she died shortly after arrival.
The Mirror reports that friends of the girl - described as 'beautiful' and 'effervescent' by her distraught family - speculated that she had taken PMA, or pink ecstasy, which is similar to MDMA and often traded as ecstasy.
Her friends said the pills were being sold locally for as little as £3 each. The 16-year-old boy has been arrested on suspicion of intent to supply an illegal drug.
Martha's parents issued a statement via Thames Valley Police and said they were 'devastated' by her death.
"Our beautiful girl was taken away from us yesterday. She was the most extraordinary, effervescent human being and all her family and friends felt so privileged to have known her," they said. "We are all utterly devastated and have sought such comfort in the beautiful condolences we have received from everyone."
The police warned other youngsters to avoid dabbling with illegal drugs such as MDMA.
Detective Inspector Brendan Murray from Thames Valley police said the force's initial inquiries led them to understand Martha had taken what 'she believed was MDMA'.
"It would be wrong to speculate on what this substance was or what caused her death, as the investigation is still at an early stage," he said. "A full post-mortem examination will be carried out tomorrow, which will include toxicology and histology tests. It is likely to be several weeks before the results of these tests are known."
"I would strongly urge young people not to take or experiment with illegal drugs such as MDMA. They are extremely dangerous and often contain poisons and illicit chemicals which can prove fatal."