The killer of a hard-working father, who was stabbed with what is believed to be a samurai sword in front of shoppers and children, was being hunted last night.

Witnesses spoke of a row between 31-year-old scaffolder Robert Dunne and a gang of youths outside the Post Office in West Lane, Middlesbrough.

As Mr Dunne turned away, one of the youths pulled out the blade and stabbed him in the back at 2.45pm on Saturday afternoon.

The gang ran off, leaving Mr Dunne lying in a pool of blood. Horrified onlookers tried to give him first aid and called an ambulance.

One teenage witness said: "He was only hit once in the back but it was a terrible wound and there was blood all over the pavement.

"There were lots of people about. It was just a normal Saturday afternoon until this happened. It was a real shock."

Paramedics rushed Mr Dunne to Middlesbrough General Hospital but he died shortly after arrival.

He was described as a well-known and well-liked member of the community, living with his girlfriend, Julie, and their nine-month-old son, Liam, in nearby Connaught Road.

Acting Detective Superintendent Gordon Laing said: "We have had it reported that a samurai sword was used.

"I must stress that we have not found the murder weapon and at this stage we cannot confirm what it was. Certainly it was a very sharp bladed instrument.

"Robert Dunne is well spoken of in the community, a popular man who got on well with people.

"On that day, he went to the area near his home and encountered these young people. For some reason - we don't yet know why - an argument broke out.

"It led to a vicious, brutal assault with this bladed weapon which caused horrific injuries from which he bled to death. This has sent shockwaves through the community."

Several witnesses have already come forward to say that the weapon used was a samurai sword.

One tearful friend said: "Everyone knew him as Donny. He was a smashing lad and a good father to his little boy. He thought the world of Liam, and Julie is going to be devastated by this - I feel so sorry for her. His mother and father live in the area and they will be distraught."

"He was a hard-working lad, a family man and for him to be murdered in the street like is just unbelievable."

After the attack, police cordoned off the area and set up a major incident room before beginning door-to-door inquiries as the hunt for the youths got under way.

Detectives have launched a murder investigation and 50 police officers are now searching for clues.

Officers will be using footage from a CCTV camera, which is positioned only six metres from the murder scene.

Acting Detective Superintendent Laing appealed for anyone in the area at the time to come forward.

"Anyone who is prepared to use that level of violence has no place in our community and it is vital that people tell us what they know," he said.

"This has had an absolutely terrible effect on his family and friends and they are having great deal of difficulty coming to terms with it.

"Those responsible have left behind a devastated family and a baby boy who has lost a father."

Anyone with information is urged to call police on (01642) 303188.