Group of 20 young men board Luas and assault passenger
A Garda spokeswoman said that Gardaí attended the scene, and the perpetrators "dispersed".
Gardaí and Transdev, the company which operates the Luas service, are investigating an incident in which a group of 20 young men boarded a tram and assaulted a youth on Tuesday evening.
According to Gardaí, the incident took place at approximately 5.40pm at the Parnell Street stop on the Luas Red Line.
A Garda spokeswoman said: "Gardaí were alerted to an incident of youths at the Luas line at Parnell Street assaulting a youth this evening.
"A number of Garda units attended the scene and youths had dispersed upon arrival."
It is not currently clear whether anyone was injured in the attack.
According to the Irish Times, one witness to the incident claimed that one of the young men who boarded the tram appeared to be "brandishing what looked like a butcher's knife".
The witness added that it may have been a prop, but that it did resemble a large knife.
The passenger described the incident as "frightening", and said that other passengers were "very concerned".
"You weren't sure if you were better getting off the Luas. No one really knew what was going on," the witness said.
Another witness to the incident told the Irish Independent that the Luas driver was an "absolute hero".
The witness said that the driver assured passengers that the incident was caught on CCTV, which should enable the Gardaí in their investigation. The driver also used the speaker to tell those involved that the Luas wouldn't be moving until they get off.
A third witness told The Irish Sun that there was "a lot of screaming, shouting, fighting [and] punching" one carriage away from them.
The passenger added that after the group left and the tram approached Marlborough, the driver stopped the tram as he worried that the group were waiting for the Luas there.