A teenager who was fatally stabbed in a council headquarters in west London was attending a knife awareness course.
Hakim Sillah was attacked in the youth offending service department at the Hillingdon Civic Centre in Uxbridge on Thursday.
The Met said a group had gathered at the venue when a fight broke out. The 18-year-old was taken to hospital but died an hour later.
A 17-year-old boy who was arrested on suspicion of murder remains in custody.