FOUR knife murders in 24 hours in London `graphically illustrates' the need for everyone to pull together and end the violence, the capital's top cop has said.

Sir Ian Blair, the head of Scotland Yard, said his officers were doing `everything possible' to catch those responsible and defend others from the same fate.

Sir Ian spoke out after it emerged a fifth man was fighting for his life in hospital after being stabbed in an attack in the city.

The man, in his late 20s, had stab wounds to the back and stomach. The four murders took place with 17 hours of each other. Sir Ian said: "There has been a tragic death toll from knife crime in London over a 24 hour period.

"Four men have been killed - one a teenager - and a fifth remains critically ill.

"Detectives have made arrests in three of the four murders.

"I want to reassure the public that the Met is doing everything possible to get knives off the streets.

"This dreadful loss of life graphically illustrates the need for everyone to pull together to put an end to this unacceptable violence."

Last week Deputy Commissioner Sir Paul Stephenson revealed a 75-strong task force had been set up at tackle knife crime. Thousands of people have been stopped and searched as part of a drive to deter young people from carrying knives.