Sgt Bill Forth, 34, died early yesterday in a pool of blood after being stabbed despite desperate efforts by a colleague and people living near by to save him.
John Stevens, Chief Constable of Northumbria, said: 'This incident is a tragic example of the extreme dangers faced by police officers going about their daily duties in protecting the public.
'This young officer was highly respected by his colleagues and only recently commended by a Crown Court judge for his courageous actions during a firearms incident.'
Sgt Forth and Constable Bill Hay, 35, went to the Clover Hill area of Gateshead, Tyne and Wear, after a report of a disturbance said to have involved a gang of youths threatening a teenager. PC Hay went to investigate, but raced back to the patrol car after receiving a call for help from Sgt Forth over his pocket radio. He found him struggling with two youths, and arrested one after a brief chase.
But members of the public then told him the sergeant had been seriously wounded, and they took custody of the suspect so the constable could help his colleague. But despite his efforts Sgt Forth died in hospital.
Sgt Forth, 34, from Sunderland, was married with two children, Christopher, 10, and Rebecca, 7. His widow, Gill, was being comforted last night by family and friends.
A post-mortem examination showed that Sgt Forth died from multiple injuries. It is understood he was beaten with a wooden post before he was stabbed.
Northumbria police said last night they were questioning a 15-year-old and a man of 25.