A teenager has been charged with the murder of an 18-year-old man at a knife awareness course in west London.
Police said a group of youths had been attending a by appointment event at the council-run youth offending service in the building when a fight broke out.
Police were called at 4pm on Thursday to reports of a stabbing at the youth offending service in Hillingdon Civic Centre.
Officers and London Ambulance Service attended and found Hakim Ishmael Daba Sillah with a critical stab injury.
Mr Sillah was taken to a west London hospital where he died at 5.25pm.
A 17-year-old boy arrested on suspicion of murder has now been charged and will appear before Uxbridge Magistrates' Court on Saturday.
Mr Sillah's next of kin continue to be supported by specialist officers, and a post-mortem examination will take place.
A second male suffered a stab wound during the incident.
His injuries were not life-threatening.
In a statement, Mr Sillah's family said: "Hakim was a lovely lad who cared about his family and preferred spending time at home with his family.
"He loved looking after his little brother, who had been ill. The parents and family of Hakim would be grateful for any information from members of the public to help this investigation."
Prime minister Boris Johnson, who represented the constituency of Uxbridge and South Ruislip before the election was called, tweeted on Friday: "Very sad news from Uxbridge last night. My thoughts are with the victim's friends and family."
Asked if people had been screened for weapons before entering the civic centre, Hillingdon Council said in a statement: "The matter is being investigated by the police and we are unable to comment further at this time.
"Our thoughts are with the victim's family."
The Press Association
