Four men remain in custody after being arrested in Dublin for conspiracy to murder as part of an investigation into the feud between the Hutch and Kinahan crime gangs.
A firearm and silencer were also seized by gardaí in last night's operation in the north inner city.
The four men, aged 23, 35, 37 and 38, were arrested in coordinated interceptions.
Speaking at a news conference at Harcourt Square Garda Station, Assistant Garda Commissioner John O’Driscoll said the plan was an elaborate enterprise with getaway vehicles that the suspects planned to destroy without being caught.
He said gardaí have followed up with ten searches, with seven cars and vans recovered, which are being technically examined.
He described this as one of the most extensive organised crime operations ever carried out by gardaí.
Armed officers from the Emergency Response Unit stopped a car on Philipsburgh Avenue in Fairview and arrested two men at around 8pm last night.
The two other men were arrested on the southside of the city.
All four are well-known to gardaí.
Gardaí say yesterday's operation was one of the most significant of its type ever undertaken in the State pic.twitter.com/4FElkFLUpw— RTÉ News (@rtenews) November 7, 2017
One is a senior figure in the Kinahan gang and a convicted drug dealer, while two others are suspected gunmen from west Dublin.
The two men from west Dublin are suspected of having been hired as hitmen by the Kinahan gang.
One of that pair was released from prison earlier this year after serving a sentence for firearms offences. The other was the victim of a gun attack a few years ago.
The fourth man is also an associate of the Kinahan gang with more than 50 convictions, including for bomb and firearm offences.
The arrests have been described as significant.
Gardaí say they believe their actions have prevented an attack on an associate of the Hutch gang who lives in Marino in Dublin.
The man was aware his life was under threat.
The four men are being held under anti-gang legislation and can be questioned for up to seven days.
Asst Commissioner O'Driscoll said considerable resources have been put into the investigation, and that gardaí have made over 40 interventions where there was a threat to life.
Speaking on RTÉ's News at One, he said the experiences of members of the force in Limerick has shown that gangs who participate in organised crime will, after interventions by An Garda Síochána, "decide that it is not in their interest to continue" such activity.