About six of the estimated 20-strong vigilante group who stormed a repossessed house in Co Roscommon and beat eight security workers were not wearing masks during the raid.
Gardaí believe they have identified those men and the ring leaders, including one man from the Roscommon area regarded as a central figure in the raid.
Two suspects were arrested in Co Roscommon on Wednesday morning and were being questioned on suspicion of assault and criminal damage, including burning out four vans and two cars.
A truck that gardaí believe the raiders used to get to and from the attack has been found. A firearm has also been discovered and sources said a gun was used to threaten the security workers during the weekend attack.
However, it was unclear whether the gun seized during searches in recent days was the same one carried by one of the gang members during the group attack, which has been widely condemned.
As well as a firearm, the gang members were also armed with baseball bats and assaulted the eight security workers in the house.
Dissident republicans
During the attack, a dog was also fatally injured and six vehicles owned by the security workers were set alight. Gardaí believe the gang arrived at the scene in a cattle truck.
Investigations since the raid at the McGann family home at Falsk near Strokestown in the early hours of Sunday morning have reinforced the Garda's suspicions that dissident republicans were involved.
Having identified many of the attackers, gardaí believe the vigilante group was a mix of local people, some with dissident links and others with no previous involvement in crime, along with dissident republicans from Dublin and Meath.
The Special Detective Unit, which investigates terrorists, has been aiding gardaí in Roscommon with the inquiry.
A number of searches took place in Dublin, Meath and Roscommon on Monday and Wednesday. As well as the truck and firearm found, gardaí have also taken mobile phones and documents for examination.
After the attack, the security workers were either taken to hospital or fled the house in Falsk. On Monday, the McGann siblings moved back into the property.
