A 15-year-old boy who was stabbed to death in Brixton on Thursday night was a pupil at Walworth Academy in Southwark.
Police officers, London Ambulance Service and London's Air Ambulance were called to the Loughborough Estate in Brixton on Thursday night and found a boy suffering serious injuries, believed to be stab wounds.
Junior Nkwelle, aged 15, was pronounced dead at the scene.
In a letter to parents of academy pupils published on Friday night, executive principal Devon Hanson wrote: "Junior was a good young man of whom the school had great hopes and who was muched loved by his friends, class mates and teachers.
"It is not an overstatement to say that the staff and students who knew this friendly, promising young man are all devastated at his tragic death."
Mr Hansen said that counselling would be available for students at the academy.
He added: "Junior and his family are in our thoughts and we will all miss seeing his smiling face around the school."
Detective Chief Inspector Charles King said: "We would appeal for anyone who has any information or witnesses to come forward as soon as possible."
Anyone witth information that may assist the inquiry should call detectives on 020 8721 4054 or Crimestoppers anonymously on 0800 555 111.
A 14-year-old girl has been arrested on suspicion of murder and remains in custody at south London police station.