A man armed with what is believed to have been an imitation firearm threatened a security man and took a cash box near an ATM.
The incident happened at Clare Hall in north Dublin at around 10.50am on Thursday.
The two raiders fled the scene in a Toyota Yaris which was abandoned at nearby Cara Park in Coolock.
A garda spokeswoman said the car has been seized and is being forensically examined.
Gardai at Coolock have appealed for witnesses.
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