A group of up to 70 youths gathered in The Square before engaging in a brawl which lasted for up to 15 minutes.
Gerard Harrington, who lives in a nearby estate, was out for a walk at the time of the brawl and happened upon it after hearing shouts from a short distance away.
“When I came around the corner, there were girls with young kids in prams and they were scurrying up the road,” he said.
“It was very distressing for kids to see that. This didn’t happen on a dark night.”
Mr Harrington said he witnessed some people spill out onto the road fighting, and that there were multiple smaller fights happening concurrently in clusters.
“At one stage they got a guy on the ground,” he said.
“What we saw was savage. There were five or six of them laced into one guy on the ground.
“One of these nights there’ll be a fatality, and that’s not an exaggeration. It’s just sad to see.”
It is understood video footage from a number of different angles is being analysed by gardaí in order to identify youths who were involved.
Niamh, another local to the Mount Oval area, told The Echo she hadn’t witnessed the incident itself, but had seen a number of videos on social media.
“These guys are brainless and bored. That’s what it is. They met here because of the space not because of the place,” she said.
She added that she had been told youths had travelled from as far away as Ballincollig and Carrigaline, but said that for that amount of people to gather would have taken some time, and said the Gardaí should have been called immediately.
“If people had seen the gathering of teenagers, that’s obviously what was going to happen, so they should have called the guards then.”