Two men have died and several others were injured in a spate of stabbings in Birmingham, London, Manchester and Sheffield, reports The Guardian.
The youngest victim, a 14-year-old boy, is in a critical condition after being stabbed outside a mosque in Birmingham.
Police said the teenager suffered several stab wounds in the attack in the Small Heath area shortly after 1am on Saturday and was taken to hospital by paramedics.
A cordon has been put in place at the scene in Herbert Road while specialist teams carry out forensic investigations.
Det Insp Jim Colclough, from the complex crime investigation team at Bournville Lane police station, said: “An investigation is under way to identify those responsible.
“This is a tragic event which has left a young boy is in hospital fighting for his life, so I’d urge anyone who was in the vicinity, saw what happened, or has any other information which may help our investigation to contact me or my team on 101 or to call Crimestoppers as soon as possible.”
In London, a murder investigation has been launched after a man, who has not been named, was found with stab wounds and later died.
Police were called to reports of a disturbance in Ropery Street in Bow at about 2.30am on Saturday. They found the victim who had been stabbed in nearby Eric Street.
He was treated at the scene by paramedics from the London Air Ambulance service before being taken to a hospital, where he died at 4.52am.
A Met police spokesman said no arrests had been made: “His next of kin have been informed. Formal identification is yet to take place. A postmortem examination will be held in due course.”
In Manchester, police are appealing for witnesses after a man was fatally stabbed during a large fight near Deansgate in the city centre.
At about 2.50am police were called to reports of a large fight involving men and women, which is believed to have began in the Suburbia nightclub.
A 21-year-old man was treated for stab wounds to his neck at the scene but died as a result of his injuries.
Several other people were taken to hospital with injuries, including a man who had been hit with a glass and two women, aged 19 and 21, who were left unconscious after being punched.
In Sheffield, five people have been injured in two linked stabbing incidents in the city centre.
Four people have been arrested in connection with the incidents, which took place early on Saturday morning, South Yorkshire police said.
In a series of tweets, the force said: “We are dealing with two linked stabbing incidents in Sheffield city centre in the early hours of Saturday. Five people were injured.
“Four people have been arrested and detained in relation to the stabbing incidents in Sheffield early this morning.”