A murder investigation has been launched following a fatal stabbing in north west London.
Police were called to Brent Cross Shopping Centre at 6.45 pm following reports of a group of males fighting.
Officers attended and found a 21-year-old man who had been stabbed.
First aid was started by officers and members of the public and the London Ambulance Service and the London Air Ambulance were called.
Despite the best efforts of everyone involved, the man died at the scene. Efforts are under way to inform his next of kin.
An 18-year-old man has been arrested nearby on suspicion of murder.
A second man, also believed to be aged 18, has been arrested on suspicion of affray.
Chief Superintendent Sara Leach, who is in charge of policing in north west London, said: “My thoughts are with the loved ones of the young man who has been killed in this incident.
“I would like to offer my thanks to the members of the public who came to his aid. They showed considerable courage.
“Two people have been arrested and an investigation is already under way. We will do all we can to identify and bring to justice those responsible.
“The public can expect to see a heightened police presence in the area through the rest of this evening and in the days to come.”
The shopping centre was open at the time of the incident and it is likely that there were a number of witnesses.
Anyone with information should call 101, providing the reference CAD6136/04MAY.
Information can also be provided to Crimestoppers, anonymously, by calling 0800 555 111.
