Mayor of London Sadiq Khan has said he is "incredibly concerned" about a recent spate of murders in the capital - placing the blame for rising violence on "massive cuts" to police resources.
The Metropolitan Police has stepped up patrols after four people were killed in as many days - and Mr Khan said officers from the "overstretched" force worked 12-hour shifts over the weekend.
He said officers were working "incredibly hard" to tackle violent crime, but reiterated his call for more funding from the government.
Mr Khan told Sky News: "Over the past five years we've seen across our country - in Cardiff, Manchester, Liverpool, Leeds, Bristol - an increase in violent crime, and we've seen it in London as well.
"We've made some progress but it's no consolation if you've lost a loved one or are the victim of knife crime. We need to do far more."
:: London's four days of violence
Mr Khan refuted suggestions that crime in the capital had risen as a result of his time at City Hall, with his predecessor Boris Johnson having talked up his record during the Conservative leadership contest.
The current mayor said London had suffered for having fewer police officers "than at any time since 2003", with the number now below 30,000.
Paying tribute to the efforts of officers, Mr Khan said: "This weekend they've cancelled leave, worked 12-hour shifts, cancelled rest days - they're under-resourced, overstretched and working incredibly hard.
"We've lost thousands of police staff, more than 40 youth clubs, many teachers and cuts made in public services, in preventative services. Even the Home Office's own civil servants say there is a link between massive cuts in police resources and an increase in violent crime."
The first of the latest four deadly knife attacks came on Friday afternoon, when an 18-year-old man was fatally stabbed in Wandsworth. Shortly afterwards, 19-year-old Eniola Aluko was shot dead in Plumstead.
On Saturday, a man in his 30s was stabbed to death in Tower Hamlets.
And in the early hours of Monday, a 42-year-old man was stabbed to death in Stratford.
Two people - 18-year-old Mohammed Nadir Dafallah, and a 17-year-old boy who cannot be named for legal reasons - have been charged with murder after the Wandsworth attack and are due to appear in court later.
Four others, aged between 16 and 19, have been released under investigation, and a 20-year-old man is in custody for questioning after being arrested on Monday.
Five arrests have been made in connection with the attack on Mr Aluko, but there have been none regarding the Tower Hamlets or Stratford incidents.
Detectives investigating the latter issued a renewed appeal for information on Monday, with a crime scene and several road closures still in place in the vicinity of Whalebone Lane.
Following reports of the deaths, Mr Khan came under attack from his regular critic Donald Trump, who said in a tweet that the mayor was a "national disgrace" and a "disaster".
The US president also shared a tweet about the murders written by outspoken right-wing commentator Katie Hopkins, in which she called the capital "Stab-City" and "Khan's Londonistan".
Mr Khan accused Mr Trump of "amplifying far-right activists" and being seen as a "poster boy for racists".
He added: "My concern isn't that he's obsessed with me, my concern is the amplification of a racist tweet that normalises racism - and that's wrong."