Gardai believe two of 'Fat' Freddie Thompson's deputies were behind the Ingram murder plot.
The pair, both of whom live in Dublin's south inner city, had their homes raided by armed officers minutes after gardai discovered a stash of four Ingram machine pistols and silencers in a Mulhuddart lock-up.
Officers believe that the men, who are on the gardai's most-wanted gangland list, were behind the plan to import the guns in order to mount a violent attack on rivals.
One of the men, a 26-year-old, is suspected of being the gunman who botched a hit on Martin Foley in 2008. The second is regarded as Thompson's eyes and ears in Dublin, and is considered 'Fat' Freddie's closest confidante.
According to sources, gardai swooped on the unit at Damastown Industrial Estate amid fears that an attack was just hours or days away.
A security source said: "These guns would have been used in a bloodbath. A hit squad armed with them would have a military-like level of firepower."
Technical examinations are continuing on the Ingram haul today. A man in his mid-30s remains in custody.
The guns were found in a raid carried out by Kevin Street and Pearse Street gardai at 5.15pm last Wednesday. Shortly afterwards searches were made at the Dublin 8 homes of Thompson's two deputies.
One of the men, who gardai had been tailing over the past few months, is a dangerous and erratic criminal.
The 26-year-old is from the Clanbrassil Street area of Dublin and is a longtime associate of Thompson.
Although he is a very active member of Thompson's gang, he does not have many criminal convictions.
However he is the chief suspect for the shooting of Martin Foley in January 2008 and was arrested over this attack but not prosecuted.
Foley was shot twice in the chest as he drove out of the Carlisle Health and Fitness Gym in Kimmage.
He was approached by a gunman wielding a semi-automatic machine pistol and eight shots were fired into his car. Two struck him in the lower chest and one grazed his head, but he miraculously survived.
The other man the gardai have linked to the weapons arsenal is believed to be the Thompson's chief lieutenant, and the man who directs his operation in Dublin while Fat Freddie is exiled.
The gangster, who is in his early 30s, is from the Dublin 8 area.
Last Wednesday's seizure is believed to have averted a multiple murder plot against Thompson's Crumlin rivals.
The weapons cache discovered contained four Ingram 9mm rapid-firing machine guns, four silencers, four loaded magazines, each with 16 rounds of 9mm parabellum bullets, and another bag of loose ammunition.
Thompson is believed to have been travelling between Ireland and the Netherlands in recent weeks directing the operation.