Police have arrested 17 suspected gang members in a bid to dampen "rising tensions" and prevent reprisal attacks following the murder of a teenager on the UK's busiest shopping street.
Seydou Diarrassouba, 18, was stabbed in the heart after a fight broke out at a Foot Locker sports shoe store on London's Oxford Street on Boxing Day.
Investigators said a number of gangs were present at the time of the killing and were aware of people wanting to "seek retaliation or revenge" for what had happened.
In order to pre-empt any further violence, officers yesterday conducted a series of raids across the capital arresting 17 people for a range of offences including grievous bodily harm, robbery, affray, intent to supply drugs, burglary, forgery and handling stolen goods. A large amount of cash was also seized.
It came after police bailed 11 people arrested over the murder of Mr Diarrassouba. The motive of the attack is yet to be established.
Met Police Commander Mak Chishty said: "We were aware of rising tensions in the wake of the murder and, having monitored the situation closely, including various comments that have been made on social networking sites, we felt it vital we take robust and prompt action in order to pre-empt any potential future violence. We don't want to see any other young person or anyone else lose their lives."
Further raids were expected across the capital.
Mr Chishty added: "This is just one of a series of measures we are carrying out in order to enhance the safety of the public and visitors to London.
"We will continue to aggressively pursue any lawful opportunities against those who choose to become involved in violent crime and thus protect potential future victims, in line with the Commissioner's pledge on total policing."
Mr Diarrassouba, from Mitcham, south west London, died from a single stab wound which pierced his heart.
In a statement released through police, his family said: "Our loving son and brother has been snatched away from us.
"A simple shopping trip has turned into a complete nightmare for our whole family.
"We are urging anyone who was in Oxford Street at the time of the incident to come forward with any evidence, no matter how little relevance they think it could have, to help the police with their ongoing investigation."
It added: "Whoever took his life took our backbone away.
"Seydou kept us upright and now we feel weak as we have lost a very special part of us.
"Life seems meaningless without our special son and brother.
"All we can say is 'Why?' He had so much consideration for others. We want Seydou to be remembered as the loving, down-to-earth, respectful and charismatic young man he was."
A Facebook page called R.I.P. Seydou has received dozens of tributes from friends of the victim and condemnation of youth violence.
A number of weapons were recovered at the scene and police have said they are particularly interested in obtaining videos of the fight shot on camera phones.
Another youth was stabbed on the same street just a few hours later.
The 11 people arrested earlier this week - two 22-year-olds, five 19-year-olds, three 17-year-olds and one 16-year-old - have been bailed to dates in mid-January.
Those arrested in yesterday's raids, which took place at properties in Merton, Wandsworth, Southwark and Westminster, remain in custody at various London police stations.
Anyone with information about either stabbing can contact police on 020 8721 4906 or Crimestoppers, anonymously, on 0800 555 111.