The two men, who spoke with Irish accents, were filmed fighting each other with hooked machetes on Gallows Corner in Romford, East London, at 3.50pm on Friday.
The injured man was rushed to hospital and later arrested in connection with the incident while the other man, who is understood to have links to a crime clan from Clondalkin is west Dublin, fled the scene and was still being sought by police yesterday.
On a video widely-shared on social media, shocked witnesses can be heard trying to intervene as the two men attack each other with deadly weapons in the middle of the road.
Cars were forced to brake suddenly as the men slashed wildly at each other. At one point, one of the men is on the ground as the second man hits a machete off his head. Both men appear to be injured in videos of the incident.
One witness can be heard shouting: “Someone call the police man,” before another shouts “put your f***ing weapons down you c**t”.
At this point one of the men drops his machete and tries to escape. The second man picks up his weapon and chases after him while carrying two machetes in his hand.
The first man can then be heard shouting: “I need an ambulance and the police. I need an ambulance.”
By this point the second man has got into a grey BMW while onlookers keep telling the first man to run away.
The second man speeds after the first man as onlookers shout: “run, bruv, run.”
At this point the second man gets out of the vehicle and chases the first man into a shop.
A follow up video shows the first man lying on the ground with his jeans down and a significant injury to his leg while people try to help.
He can be heard saying a name out loud as another man calls emergency services and says the victim is 23.
The victim was rushed to hospital in a critical condition but a spokesman for the Metropolitan Police said his condition has since stabilised.
“Police were called at around 15:50hrs on Friday, 13 January, to reports of a fight with knives between two people in the Gallows Corner area of Harold Wood.
“One male was taken to hospital
“The condition of the injured man, aged in his 20s, has been assessed as not life-threatening. He remains in hospital but has been arrested on suspicion of Grievous Bodily Harm.
“Enquiries are ongoing to trace the second man,” a spokesman said.
The second man’s registration plate can clearly be seen in a video of the incident and it is understood police are aware of his identity.
Sources said he has close links to a well-known crime clan based in Clondalkin in west Dublin.