A man in his 60s was rushed to hospital after he was stabbed in the neck with a bottle.
Gardai and emergency services rushed to the scene on Dorset Street Lower on Monday afternoon.
The man was taken to the Mater Hospital for his injuries, which were described as non life-threatening.
A taxi driver witnessed the gang attack in the area while driving a customer towards Dublin Airport for a flight at 5pm.
And he told RTE Liveline listeners that he was shocked that the stabbing happened in broad daylight, saying that the attacker "didn't give a damn about the consequences" of the assault.
He said: "I was going out Dorset Street just before you approach Whitworth Road, and I saw a scruffle on my left hand side.
"There was a woman and two men. They were all in a huddle together.
"The smallest lad reached to the ground and picked up a clear, glass, broken bottle with a long neck.
"It had two very jagged, pointed edges on each side. He rammed that into the other chap's neck with all the force that he could muster.
"He didn't give a damn about the consequences. He was trying to do whatever damage he could do to that man. It was as vicious as he could do it."
The taxi driver was afraid that the stabbing victim was fatally injured.
And he has been left incredibly shaken by what he saw.
He said:"The first thing I did was I rang 999. It rang out but on the second attempt I got through to a guard.
"I explained to him what I had seen and I also asked to send an ambulance because this guy could be actually dying.
"It was that serious. I was that scared. I'm still scared about it. I saw him put the glass into the neck."
A garda spokesman said : "On Monday, 7 February, 2022, shortly after 4.30pm Gardai and Emergency Services attended at Dorset Street Lower, Dublin 1, where a man in his 60s was discovered with an apparent stab wound following an incident. He was taken to the Mater Hospital for treatment.
"His injuries are not described as life threatening. Gardai are following a definite line of enquiry and are appealing for witnesses to them at Mountjoy Garda Station 01 6668600. Investigation ongoing."
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