Police confirmed a total of 36 men were detained and later arrested at London's Kings Cross underground station for fear they may cause trouble at the Notting Hill Carnival.
The large group, 19 of whom were aged under 18, was halted around 3.45pm to prevent a "potential breach of the peace," Scotland Yard said.
Revellers at the Notting Hill Carnival this year enjoyed sunshine, music and a heavy police presence. Police arrested more than 200 people.
Hundreds of thousands of revellers will flock to Notting Hill Carnival today.
Europe's biggest street festival has hit the capital with exotic dancers, vibrant music and Caribbean food livening up London.