An official from An Post, his partner and their child were abducted from a house in Co Louth before around €500,000 was taken from a post office.
A number of men, at least one of whom was armed, entered their home in Drogheda last night and held them for several hours before they were taken to another location.
The official was forced to go to the post office on West Street in Drogheda this morning and withdraw the money, which he later handed over to the gang.
The official's partner and child were released unharmed in Damastown in Dublin this afternoon.
A Silver Opel Corsa was found burned out in Clonee, Co Meath, at 11.30am.
The couple, who were both in their 30s, spent most of the 15-hour ordeal bound and gagged. The raiders spoke with Dublin accents.
Gardaí have appealed for witnesses to the gang's movements and have asked for information about any suspicious activity at a number of locations in Drogheda, Dublin and Meath.
They are keen to speak to anyone who was in the Forest Park housing estate in Drogheda, the post office at West Street, Damastown in Dublin and the Summerseat housing estate in Clonee.
Anyone with information is asked to contact gardaí in Drogheda on 041 9838777 or the Garda Confidential Line on 1800 666 111.
Minister for Justice Alan Shatter has said his sympathy goes out to the victims.
Mr Shatter added: 'I deplore the kidnapping of people and the subsequent robbery at a post office in Drogheda.
'Based on initial information I have received I have asked the Garda authorities to let me have a detailed report on the circumstances surrounding the incident, including, in particular, whether agreed procedures for dealing with this sort of incident were followed.'
