A man in his 40s has been arrested in connection with the violence at the Smithfield Horse Market last Sunday.
The man was arrested at Galway District Court this morning where he was due on other unrelated charges.
He was taken by detectives to the Bridewell Garda Station in Dublin where he is now being detained under Section 30 of the Offences Against the State Act.
He can be questioned for up to three days.
Earlier today, another man appeared in court charged in connection with the violence during which three people were injured.
John Keniry, 41, with an address at Rainsford Avenue, Thomas Court, in Dublin 8, was charged with the unlawful possession of a revolver at Oliver Bond Street on 6 March last.
He was remanded in custody for a week.