Four young men were stabbed to death in London in separate attacks, between the evening of 31 December and the morning of January 1.
As well as the four deaths, a fifth stabbing, which took place earlier in the day, left a victim in critical condition in hospital.
Police officers said the attacks, which took place in north, east and south London, are not being linked.
The Metropolitan Police condemned the ‘senseless violence’ and the ‘small groups who chose to engage in disorder and violence’ on New Year’s Day – when people should be out having fun.
The first fatal stabbing happened at 11.30am on New Year’s Eve – an 18-year-old man was stabbed in Larmans Road, Enfield and later died in hospital the same evening.
The second took place at around 7.30pm, when a 20-year-old man was fatally stabbed in Memorial Avenue, West Ham.
At around 10.30pm, a 17-year-old male was fatally stabbed in Norwood Road near the junction with Station Rise, Tulse Hill.
At around 2:35am on 1 January, a 20-year-old man was fatally stabbed in Bartholomew Court, Old Street.
A second male, aged in his 20s, was taken to hospital suffering with critical stab injuries.
Police have so far made five arrests, all relating to the stabbing in Enfield – there have been no arrests as yet in the other cases, at the time of writing.
Commander Neil Jerome, of the Met’s Territorial Policing Command, said:
There were thousands of officers on duty across London yesterday and throughout the night, all determined to play their part in keeping the public safe.
I am grateful to Londoners and visitors to the capital who co-operated with police – both at major celebrations in Westminster and at thousands of organised and private events across London – to enable the vast majority of people to enjoy New Year’s Eve.
However, there were small groups who chose to engage in disorder and violence, and whose actions have had utterly tragic consequences.
It is heartbreaking that, at a time when so many of us are contemplating what lies ahead in 2018, four families are dealing with the grief of losing a loved one to senseless violence and the callous use of knives as lethal weapons.
Commander Jerome reassured the public, those responsible would be brought to justice, adding:
I can assure Londoners – and the families and friends of the four males killed and the fifth who remains in hospital – that detectives will work tirelessly to bring to justice those responsible for such despicable acts of violence.
As we begin these investigations and the provision of support to four grieving families, days like this serve to re-enforce the determination of the Metropolitan Police to tackle knife crime and violence on our streets; especially offences committed by and against young people.
I would urge anyone with information about these attacks, and more generally about anyone who routinely carries a knife, to urgently pass that information to police or Crimestoppers.
If you’ve hesitated to do so before, then these four tragic deaths at the start of a new year may persuade you to act now to make London safer for your family and friends in 2018.
Anyone with information is being urged to contact police by calling 101.
To remain anonymous call Crimestoppers on 0800 555 111 or contact them via the Crimestoppers website: crimestoppers-uk.org.