LONDON - Two teenagers have been arrested in connection with the murder of a man stabbed to death in London's Oxford Street, police said on Wednesday.

The suspects, aged 18 and 19, were being questioned at an east London police station over the fatal stabbing of Steven Bigby.

The 22 year old from Hackney, east London, was murdered outside a McDonald's in the busy shopping district during Monday's rush hour.

A post mortem examination found he died from a single stab wound to the heart.

Police said Bigby was stabbed after an argument broke out between two groups of men on Oxford Street, one of the capital's busiest shopping areas. A drink was thrown by one of the groups and the "spontaneous" row quickly escalated.

A passing doctor gave Bigby first aid on the pavement after he was stabbed. He was taken to a London hospital where he was pronounced dead.

A bloodied four-inch knife was recovered nearby and CCTV footage was seized.

Police asked tourists to hand over any holiday photos they have taken in the area.

"We would be very keen to see these photographs as they could hold key information," said Acting Detective Chief Inspector Bob Mahoney, of the Metropolitan Police.

Knife crime has blighted London in recent months. Two teenage boys were stabbed in Holloway on Sunday, while 16-year-old Jimmy Mizen was killed in a bakery on Saturday.