Four men were arrested following a fight on the Westport to Dublin train on Saturday evening.
The incident happened after the 5.45pm service stopped at Tullamore and gardaí later boarded the train at Sallins, Co Kildare to intervene.
Two men were detained and charged with public order offences before being released on bail. Two others remain in custody. Two of the men are due to appear at Naas District Court on Monday.
One passenger, who did not wish to be named, said the incident involved at least five men. Passengers from the carriage, who were not involved, moved to another carriage to get away from the fracas, she said.
She said there was “one fellow with blood streaming from his face” and that “another guy ran up and said ‘if I don’t find my bag, I’m going to stab somebody’”.
“It was scary,” she said, adding that the row appeared to have “started over a woman”.
The woman said that gardaí boarded the train at Sallins and asked if anyone had seen a knife. “But at that stage the gardaí couldn’t find the weapon.”
A Garda spokesman said there was no stabbing incident on the train.
Irish Rail spokesman Barry Kenny said no ambulance was required for the injured man.
He said his understanding was that the incident involved was a robbery in which one group of men attempted to take mobile phones and luggage from another group.
Irish Rail has provided CCTV footage of the incident to gardaí.
