A murder inquiry was underway today after a pensioner died in hospital following an altercation involving a gang of youths.

Police were alerted to the incident by ambulance staff who received a report of an unconscious man lying in the street on Leeds Road, close to Thornbury Avenue, Bradford.

Three teams of paramedics attended the scene and took the 67-year-old to Bradford Royal Infirmary suffering from head injuries. He was later transferred to Leeds General Infirmary where he died yesterday afternoon.

The incident occurred at 7pm on Sunday as the man walked down Leeds Road. He apparently became embroiled in a heated exchange with a group of Asian youths and was struck by one of the group.

Detective Superintendent Dave Oldroyd, who is leading the murder inquiry, said: "A serious incident has taken place but it's not clear exactly what's happened.

"It's apparent that there were a number of people present when this took place and some of those people have not come forward. We would suggest very strongly that they are witnesses and we would like to hear from anybody who knows anything about this incident or was involved in any way whatsoever.

"We are not judging anybody at this stage."

Det Supt Oldroyd said police were in the process of studying CCTV images from the area.

The dead man's identity has not yet been released.

An eyewitness, who works in a nearby business, said: "A customer told me there was a row going on. I was just leaving work and saw an elderly man shouting at a group of youths.

"One of the youths reacted and punched the man. He fell backwards off the kerb and his head struck the road very hard.

"I ran over and for a moment I didn't think he was breathing. I was going to put him into the recovery position but then someone said it was better to phone an ambulance.

"He was only hit once but the way he fell meant his head hit the road first and he fell off the curb so the full impact was on his head."

Another local businessman said he had first become aware of the incident when the paramedics arrived.

"I heard the sirens and looked out to see what was happening," he said. "At first I thought it must have been a car crash. There were three ambulances, then one of them left and I saw the man being put into an ambulance. The police arrived then and sealed off one side of the road with tape. The road was sealed off until about midnight."

A police spokesman said: "From inquiries conducted so far, it appears the victim had been walking along Leeds Road when he became involved in an argument with a group of Asian youths and was then assaulted. The area would have been busy at the time and detectives are keen to hear from anyone who was in the area and witnessed the incident."

Anyone with information should call detectives on (01274) 376259 or Crimestoppers anonymously on 0800 555111.