The five, who include two women, are being held at Henry Street and Roxboro Road Garda Stations under section 30 of the Offences Against the State Act.
A handgun found during the raids has been sent to the Garda ballistics section in Dublin for forensic examination. Up to 50 gardaí carried out the raids on houses in Southill, Ballinacurra Weston and St Mary’s Park.
One of the men arrested is a known member of the McCarthy-Dundon gang.
Members of the Armed Response Unit backed up members of the divisional search team during the raids which commenced at about 7am and went on until early afternoon. The search is part of an ongoing operation to tackle people involved in serious gang crime in the city.
Armed patrols have been increased in Limerick in recent months, as known members of the McCarthy-Dundon gang moved back to the city having left in the aftermath of the Shane Geoghegan murder last November.
The movements of known key members of the gang are being closely monitored by Garda surveillance teams on a round-the-clock basis.