Britain's most senior policeman has said children lured into gangs should be treated like victims of abuse.
Kodjo Yenga was murdered by a gang in Hammersmith, London
Sir Ian Blair said children who face pressures from within their own families to join gangs should be placed on the child protection register.
The Metropolitan Police Commissioner told the Guardian there was a need to "think outside the box".
He said he was suggesting taking a "child protection approach" to stop them getting involved.
Sir Ian was speaking as a report on gangs in London was published by the Met.
He said: "While the response of the Metropolitan police and other forces will be extremely robust around youth violence when it is committed, we should also be thinking about how to stop children drifting into these gangs.
"One of the ideas I have asked to be explored is that where an older sibling is clearly involved in gang activity, the right way forward is that there should be a child protection approach for any younger sibling who is clearly at risk of moving into a lifestyle which is extremely dangerous to that child."
The report says there are at least 171 street gangs operating in London - although the figure could be much higher.
While 90% of the gang participants are male, it is believed that there are three female gangs operating in the capital.
Claudia Webb, a senior adviser to the Met's Operation Trident, which tackles gun crime, said protecting children was a "fundamental part" of society.
"Local authorities have a duty to protect children from crime and from the fear of crime," she said.
"Unfortunately there's never been the proper joined up thinking to fully implement that part of the legislation."
Cindy Butts, vice-chair of the Metropolitan Police Authority (MPA), told the BBC she agreed with Sir Ian.
"If we know there are risk factors and those risk factors might include issues like exclusion from school, it might be a lack of a role model, a male role model within the home, there might be issues of deprivation and living in an inner city area... as we know the risk factors, why are we not dealing with those risks?"
Peter Herbert, childcare lawyer and independent member of the MPA, said the state needed to help improve the self respect of young people.
"You work in partnership with young people to make sure gangs are not attractive to them and particularly criminal gangs and you give them alternatives of employment, of education, and support and self respect," he said.
Ian Johnston, chief executive of the British Association of Social Workers, said young people who drifted into gangs were often victims themselves and needed help.
"I don't think we can generalise. I think Ian Blair's notion would be welcome if it spells a greater acknowledgement of the fact that many young people who get into trouble are themselves victims and need care.
"But it's not helpful if it embodies the get tough philosophy that assumes that we can compel young people to do what we think's right for them."
Norman Brennan, director of the Victims of Crime Trust, said: "We welcome any initiatives that will safeguard children and make society a better place.
"But this is too little, too late. What about the true victims? They are the ones that have done nothing wrong.
"If we're going to put children on the register in this way then Ian Blair should also not just beat his chest but launch a massive investigation, to bring the family members putting pressure on children to join gangs to justice."
A spokesman for the Met Police said: "The Commissioner has not suggested that taking children into care was the way to 'stop gangs'.
"The point he is making is that he considers it worth exploring whether dealing with children at risk through a child protection approach, where a range of agencies work together to protect and minimise the vulnerability of a young person at risk, could be effective."
Bob Reitemeier, chief executive of the Children's Society charity, said he welcomed Sir Ian Blair's comments.
"At every stage, children should be given a chance to extricate themselves from danger.
"Very often they don't realise what they're getting into. They don't understand the level of violence they're opening themselves up to. It's our responsibility to protect them."