Theresa May and Amber Rudd have been "absent while violent crime surges" across the country, MPs claim, amid calls for action to make London safer.
Labour leader Jeremy Corbyn is among a group of 47 MPs urging the Prime Minister and Home Secretary to agree to an urgent meeting with them and London mayor Sadiq Khan to discuss how the Government is planning to tackle "rising levels of violence".
They argue Mrs May and Ms Rudd have shown "no signs of changing their approach", with communities "crying out for national leadership" on the issue.
Ministers also "cannot just blame" Labour's Mr Khan and pretend the Government has no responsibility, the MPs add.
The letter co-ordinated by Ilford North Labour MP Wes Streeting was sent to Downing Street and the Home Office following a flurry of violent attacks in the capital, where more than 50 people have been killed since the start of the year.
It states: "Violent crime has been on the rise since 2014 and in recent weeks we have seen too many lives lost on the streets of London to guns and knives. This is neither acceptable nor inevitable.
"More must be done to tackle both crime, and the root causes of crime.
"That is why we are calling on you, the Prime Minister and Home Secretary, to urgently meet with us, along with the mayor, to discuss what more must be done to make our city safer."
The MPs warn of the impact of funding cuts to the police while probation and prisons are "in chaos", meaning criminals are leaving "violent and crime-ridden jails unreformed".
They also voice concerns over difficulties faced by schools, the health service and youth services, plus the need for social media companies to take down videos and posts which are "fuelling" the rise in violent crime by "glorifying and amplifying" violence.
The MPs add: "To us, and to many Londoners, both the current Home Secretary and the Prime Minister have shown no signs of changing their approach.
"In fact, both have been absent while violent crime surges across the country. Communities are crying out for national leadership on this issue."
They also say Mr Khan and the country "desperately" need the Government to "step up to the plate", with urgent action needed to stop "violence becoming normalised".
The MPs who have signed the letter are all Labour and predominantly represent London constituencies.