A young father laying dying from stab wounds as his attackers walked away from the scene "laughing and joking," according to locals.
Eddie Fitzgerald (29) from Westpark Drive, Finglas, was visiting Larch Hill apartment complex in Santry when he was attacked by three youths.
The vicious stabbing happened in broad daylight and young children watched on in horror as the man lay dying on the pavement.
Two women described how they tried in vain to keep the victim conscious and covered him in blankets, comforting him in his last moments.
Mr Fitzgerald was the father of a baby girl. Gardai are working on the theory that the row erupted over a debt owed to the victim.
A resident, Lisa Tyrrell (31), whose family apartment has a balcony overlooking the parking area where the incident occurred, said she just returned from the school run when the argument broke out.
"I arrived from bringing my daughter from school around two o'clock when I saw him having an argument outside the building with three young fellas in tracksuits and hoodies," she said.
Ms Tyrrell met her niece Amy Crowley (21) who had come to visit her with her own son. The two women went upstairs to her flat but as soon as they arrived they could see from the balcony something was very wrong below, they said.
"He had already been stabbed when we arrived but we didn't realise it ... The young fellas had just walked off laughing and joking," Ms Tyrrell said.
The women heard Mr Fitzgerald's friend shouting to him: "Get in the car and I'll drive you to the hospital." But he replied: "No, ring an ambulance, I can't make it."
Ms Crowley said: "He collapsed on the ground. We ran down to help. We put blankets over him. He had two stab wounds on his leg and one in his arm and one in his chest.
"We held him and tried to keep him warm. We tried to make him stay awake but he was unconscious. There was no life in his eyes."
Ms Tyrrell said she had heard that Mr Fitzgerald was mourning his recently-deceased grandmother and had been taken for a drive by a young friend.
"It's tragic. One of his parents has lost a son and a mother on the same day," said Ms Tyrrell.
They said Mr Fitzgerald's friend ran over to a green area to find part of the knife used by his attacker that had been discarded on the grass.
"When he came back, he kept saying to the man 'Eddie, Eddie, please. You'll be okay'," said Ms Tyrrell. "Children were watching us from the balcony as we tried to help him."
A young woman said: "Eddie was a great father and a well-loved friend. He had a lovely daughter Amelia, who is not even one year old yet."
Gardai later arrested a man aged 22. He was detained for questioning at Ballymun garda station. The suspect is believed to be from the Larch Hill apartment complex. Gardaí are appealing for anyone with information about the incident to contact them at Ballymun Garda Station on 01 6664400.