Children as young as six are carrying knives and 10-year-olds are arming themselves with weapons out of fear, the country's top police officer has been told.
Metropolitan Police Commissioner Cressida Dick heard children "feel naked" without them, while some are too scared to cross the capital's roads unarmed.
Ms Dick vowed to get to the root of knife crime as she visited a youth centre in Putney, south-west London, meeting community leaders, reformed gang members and the family of Lewis Elwin - a 20-year-old trainee electrician stabbed to death in Tooting last year.
The Commissioner promised more officers in schools and others in every ward to help build relationships with young people.
She was told community groups are "screaming out" for a relationship with police, but the force is "not following up".
One woman told Ms Dick knife crime affects children far younger than the teenagers and young men normally associated with it.
She said: "On the housing estate, it's six-year-olds that are carrying knives, because they think they won't be stopped. You need to start there, in the primary schools - you need to tell much younger people."
Josh Osbourne, a mentor at youth charity Carney's Community, said 10-year-olds live in fear, saying: "They can't even cross the road because they're at odds or in a dispute with somebody else from literally the same postcode but across the road."
Andy Smith, from social enterprise The Feel Good Bakery, told Ms Dick young people carry blades for protection, saying: "They say they feel naked if they haven't got their knife with them."
The capital has seen a wave of knife attacks in recent weeks, with more than a dozen people killed or seriously injured.
Scotland Yard launched the latest phase of Operation Sceptre earlier this month, cracking down on knife crime.
But despite more than 70 arrests for possession of offensive weapons and knives, within a week three more people had been fatally stabbed.
Speaking to the Press Association after the meeting, Ms Dick said it was "pretty horrifying" to hear of armed six-year-olds.
She said: "It's outrageous to hear a six-year-old is carrying a knife, for whatever reason.
"That's something a police officer by themselves or even a police force isn't going to be able to have very much impact on. The question there is what are the parents doing? What are the school doing?"
Ms Dick said youngsters often carry knives for "some kind of respect, some kind of kudos", but added: "I do accept there are places where some of our young people are scared and they feel it makes sense to carry a knife.
"I can say as long as I live that it does not make them safer. They may not hear that message from me... we need to get people in communities, we need to get people in schools, we need to get parents understanding and helping young people to understand... it will end in tragedy, probably, for them."
Outlining her plans for early intervention to tackle the epidemic, Ms Dick said: "I want to shift us further into prevention. I want all of us to be working on stopping this before it happens.
"Community groups will be an incredibly important part of that. We need to play our part, but it is only a part."
The Commissioner still has work to do to reach those communities - Mr Osbourne said the meeting was "about as much use as a chocolate teapot".
He added: "We have realised that the things that we need, the Commissioner is unable to provide."