A flurry of attacks in London on Thursday compounded a recent violent crime spike in the capital.
Six more stabbings occurred yesterday, meaning more than 50 people have been killed in the city since the start of the year, more than 30 of whom were fatally knifed.
The pressure on murder detectives is now so great that Scotland Yard has enlisted the support of City of London police to help cope with the caseload.
In the latest spate of stabbings, six youths were attacked within a 90-minute period, including a 13-year-old boy who was seriously wounded after being set upon in Newham, east London, shortly before 7pm.
Three youths were arrested on suspicion of grievous bodily harm with intent, Scotland Yard said.
Around an hour earlier, two 15-year-olds were seriously hurt after being stabbed in Grove Road, Mile End, east London.
A male was arrested on suspicion of attempted murder and another youth, 16, who was treated for minor injuries, was arrested for conspiracy to commit grievous bodily harm, Tower Hamlets police said.
The attacks have added to the UK's soaring rate of knife crime, with fatal stabbings in England and Wales at their highest levels since 2010/11.
The escalating violence has been especially acute in the capital, with one former senior police officer saying Scotland Yard appears to have lost control of London's streets.
Victor Olisa, the Met's former head of diversity and head of policing in Tottenham, told the Guardian: "It appears to people I have spoken to as though the police have lost control of public spaces and the streets.
"The silence from senior officers in the Met is deafening."
Mayor of London Sadiq Khan said the rising number of murders on the capital's streets was "heartbreaking" and criticised the government for cuts to the policing budget.