Communities minister Ruth Kelly says the recent spate of teenage killings amount to a series of isolated incidents, not a trend "sweeping the country", but others fear a permanent trend of rising youth violence.

NO - Lee Jasper, director of equalities and policing for the Mayor of London

While these are tragic events, they are isolated incidents. The reality is that overall crime in London has dropped by seven per cent and violent crimes have gone down by five per cent.

However, even one incident is one too many and that is why the Mayor has put more police back onto the streets of London.

The success of Operation Trident has shown that partnership working between the police and local communities does work.

YES - Rev Nims Obunge, chief executive, The Peace Alliance

I don't think that we can call what's happening "isolated". If we accept there are fashion trends, then we accept there are trends in other areas of life.

The trend discovered from working with Operation Trident is that the age range involved in crime has got lower and lower each year.

There needs to be a shared response from the community, police and government. We have got to have more statutory youth provision for our young people.

NO - Clare Thomas, chief grants officer, The City Bridge Trust

The truthful answer is: we don't know. Real statistics - rather than headlines - are not reliable on this issue. Official statistics fail to measure a large amount of violent offences because of different recording mechanisms.

Evidence from young people themselves is that the carrying of knives is on the up.

To help young people stay away from knives we need to work with the police, schools, parents, community leaders and peer groups.

YES - Geoff Thompson, executive chairman, Youth Charter

The association of knives with gangs as a method of protection is nothing new. It has been an issue for many high-testosterone young males who are experimenting with aggression that if unfocused or unchannelled becomes violent.

The current and increased instances of knife carrying, knife use and its tragic consequences are due to the lack of regular challenging and structured physical activity, which provides an outlet for aggression.