Gardaí have arrested a 21-year-old man in connection with the firearm incident in Smithfield on the morning of Sunday, March 6.
He is presently detained at The Bridewell garda station under section 30 of The Offences Against The State Act.
This brings the total arrested in relation to this incident to four.
Two males received injuries during the incident in which as suspect device was also found.
Gardaí have appealed for witnesses to this incident or to anyone who may be able to assist with the investigation to contact the incident room at the Bridewell garda station on 01-6668200, the Garda Confidential Telephone Line 1800 666 111 or any Garda station.