New Year London stabbings: Number of deaths 'unusual'
The murders of three young men and a boy in unrelated attacks across London over New Year were "highly unusual", the Metropolitan Police has said.
A 17-year-old boy and two men, aged 18 and 20, died on New Year's Eve, while a 20-year-old man died after being stabbed in the early hours of the following morning.
A fifth victim is critically ill in hospital.
Six people have been arrested in connection with two of the attacks.
Deputy Commissioner of the Met Police, Craig Mackey, said the number of violent deaths over a 24-hour period was highly unusual and that detectives were working around the clock to bring those responsible to justice.
"Millions of Londoners celebrated New Year's Eve peacefully and safely, but four families who lost loves ones in violent circumstances got the worst news imaginable and our thoughts remain with them and everyone affected by what has taken place", he said.
"We have made arrests in two of these cases, with active lines of inquiry in each of the investigations being pursued.
"We would urge anybody who has any information about these murders that might assist detectives to contact police.
"Tackling serious violence and knife crime in London remains a number one priority for the Met, but Londoners need to pull together to tackle this issue."
Scotland Yard said a 19-year-old man had been arrested on suspicion of murder over the New Year's Day stabbing of a 20-year-old man at a house party in Bartholomew Court, Old Street, Islington, north London.
Five males, aged between 17 and 21, have also been arrested in connection with the death of an 18-year-old in Larmans Road, Enfield, north London.
In the other attacks, a 20-year-old man was fatally stabbed in Memorial Avenue, West Ham, and a 17-year-old boy was killed in Norwood Road, Tulse Hill, on New Year's Eve.
The fatalities in the final hours of 2017 took the number of people stabbed to death in the capital last year to 80, the Met said.