Three men - including two teenagers - have been arrested following the death of a schoolboy who collapsed after taking ecstasy at a rave.
It was revealed that before 16-year-old Daniel Spargo-Mabbs set off for the event, he told his worried mum: "I love you Mum. I promise I won't die."
Daniel was rushed to hospital on Friday but tragically died on Monday.
The teens in custody are aged 18 and 19. They were arrested on suspicion of supplying a controlled substance.
Daniel's devastated mum Fiona, 46, paid tribute to her son.
Speaking at her home in Croydon, South London, with dad Tim, 50, she said: "This is all so unreal. I don't know how I can go on.
"Daniel had never taken drugs before. It is not the kind of thing he did. He knew the risks.
"Danny always used to say, 'I love you too mum, I promise I won't die.' That's exactly what he said when he went out on Friday. He didn't keep that promise. But he didn't know. If he had, he wouldn't have done it."
Daniel, a pupil at Archbishop Tenison's Church of England High School in Croydon, went to the unlicensed rave in Hillingdon, West London.
He was a pupil at Archbishop Tenison's Church of England High School in Croydon, where headteacher Richard Parrish paid tribute to him as a bright, articulate boy with 'huge potential'.
Mr Parrish said: "He was going to go far. We are still stunned. We're just beginning to emerge from that."
The teenager, who was in the first year of studying for his A-levels, was 'just beginning to find his niche' and was interested in 'a whole range' of things, the teacher said.
He wrote a letter to parents to express the school's grief.
It said: "Sometimes you hope that the worst thing won't happen. Sometimes it does happen anyway. And yesterday it did.
"We began Monday knowing that Daniel Spargo-Mabbs, one of our Year 12 students, who has been with us in the school since Year Seven, was in a critical condition on a life support machine. At lunch time he died. In the afternoon we spoke to each year group in turn, starting with his own, to tell them the terrible news.
"Today we begin again, knowing that our school and the world is the poorer without him. Today is too soon to do anything more than react to the brutal fact that we have lost Daniel.
"Tomorrow we will begin the process of remembering, of paying tributes, of collecting our thoughts and of coming together as a community to remember him together.
"Our heart goes out to Daniel's family, to his parents, to his brother Jacob (who did his A Levels here last summer) and to his closest friends."
Mr Parrish added: "It is not normal that a bright, articulate, talented 16-year-old should be taken from us in this way. It is not normal that his school and, above all, his family should be grieving today for his loss to us.
"It is not normal that his year group and his friends should have to learn so soon in life how short that life can be."
• Two men have been charged on suspicion of supplying controlled drugs in connection with Daniel's death. Nicqueel Pitrora, 18, of Croydon, and Ryan Kirk, 20, of Beckenham, will appear at Uxbridge Magistrates' Court today.
Both face charges of being concerned in the supply of class A drugs, while Pitrora has also been charged with possession of cannabis.
A third man, aged 19, has been bailed until a date in late March, pending further investigation, police said.