An armed gang was just minutes from escaping with over €1 million from a cash delivery van yesterday when gardaí moved in and foiled the heist.
Detectives said the gang had extremely detailed information on the van's movements collecting money around Dublin city centre.
They had planned to wait until the van's crew had completed its morning collection before making off with the maximum amount of money possible.
The attempted robbery, in Swords, Co Dublin, was foiled when two men known to the driver and who were tied up by the armed robbers overnight, managed to escape and raise the alarm.
The robbery attempt was the latest in a number of robberies involving hostage-taking.
The incident began at about 8pm on Sunday. Three armed and masked men gained access to a house in the Broadmeadow area of Swords. Two of three men renting the house were at home at the time.
The men, an Irish national who works for the Chubb security company and a Romanian national, both in their 30s, were tied up. The third tenant returned to the house just after 2am after finishing a shift as a bar worker. He too was tied up by the gang.
Sometime after 3am all three hostages were taken to a derelict cottage at nearby Oldtown in north county Dublin where they were tied up.
The Chubb worker was told to report to work as normal just after 5am yesterday to the Chubb cash-in-transit depot in Dundrum. He was instructed to carry out his usual early morning city centre collections and to contact them via walkie-talkie when the round was complete.
The gang informed him that at this point he would be given instructions to meet them with his cash load of over €1 million at a city centre location.
However, one of the gang guarding the van driver's two housemates in the Oldtown property left his hostages alone sometime before dawn. The men managed to free themselves and they ran to a nearby house where they called the Garda.
The Chubb van was on Dame Street when gardaí got to it at 8.15am. Gardaí believe the money was to be handed over 30 minutes later.
The Chubb worker and his two housemates were said to be "very shaken" by their ordeal. A second Chubb employee who was manning the target van with the driver was also said to be in shock.
Gardaí in Swords and Coolock are being helped by members of the National Bureau of Criminal Investigation, including officers attached to its organised crime unit. No arrests had been made last night.
Gardaí were last night studying similarities between the attempted robbery and other so-called "tiger robberies".
One north Dublin gang whose members have stolen around €3.5 million in a number of recent armed robberies figure prominently on the list of suspects.
Members of this gang are currently on bail having been charged with serious offences involving firearms.
However, informed sources said the investigation was at a very early stage and that a number of other Dublin criminal gangs known for their involvement in armed robberies were also under suspicion. These include well-known criminals from Finglas.
Officers said the raiders' knowledge of the van's collection routine suggested they may have been given information by an industry insider.