A murder investigation has been launched after a man was stabbed to death in a fight in Islington.Police were scrambled to Tufnell Park Road at just before 7.30pm on Monday. Officers attended and found a 21-year-old man with stab wounds.A police statement said: "He was taken to hospital by the London Ambulance Service; despite the best efforts of medical staff he died there in the early hours of Tuesday, 12 December.