A family was kidnapped and tied up in the Dublin mountains last night as part of a robbery on a security van in Lucan this morning.
It is believed several million euros were taken.
A man, woman and their children were taken from their north Dublin city home during the night by armed and masked men who broke in shortly after 10pm.
The woman and her children were brought to Cruagh Wood near Stepaside where they were tied up. It is believed the man, who worked for the security van company, was then forced to go to work as normal.
A Garda spokeswoman could not confirm a report that more than €2 million was taken in the raid. A Garda statement said: "A security van was robbed in the Strawberry Beds area of Lucan this morning and an amount of money stolen".
It is understood the driver of the van was taken by the gang during the raid and brought to Kinnegad, Co Westmeath, where he was later released.
The woman and children managed to free themselves and went to Stepaside Garda Station this morning shortly before 10am.
The investigation is being carried out by the National Bureau of Criminal Investigation, and officers from a number of Dublin stations.
The Taoiseach said the robbery bore "all the hallmarks of a paramilitary group" and that it was known that paramilitary groups had "moved into criminality".
Mr Ahern said, however, the government would have to wait for an assessment from the gardaí.
He also said he wished to commiserate with the family on the trauma they had suffered.
Labour's justice spokesman Joe Costello said the robbery was an "alarming development that raises very serious questions about the adequacy of security precautions for the transit of such large sums of money.
"One would have hoped that the financial institutions and the security companies would have learned the lessons of the Northern Bank robbery and put in place appropriate precautions to prevent a recurrence."
He said there was "an urgent necessity" for the gardaí to sit down with the financial institutions and the security companies to ensure all necessary measures are put in place to prevent such robberies in the future.