Gardaí believe that raiders who tried to rob money from Ulster Bank in Enniscorthy, Co Wexford, overnight used some form of gas to try to blow open the ATM machine.
The three raiders got into the bank at about 3.30am and caused a gas explosion at the back of the ATM machine from inside the bank.
The explosion was heard 500 metres away by gardaí in the main garda station.
Two uniformed gardaí drove down to the bank and confronted the raiders.
At least one shot was fired by the raiders, who made their getaway in what is believed to be an Audi A6.
An undisclosed sum of money was taken in the raid, but no one was injured in the incident.
It is understood that the raiders dropped most of the money they were taking when they realised gardaí were at the scene.
Gardaí have not reported how much money was taken.
This is thought to be the first time such a method of trying to blow open an ATM machine has been used in Ireland.
Bank officials are aware that this method has been used on the continent previously.
Gardaí have appealed for witnesses to contact Enniscorthy Garda Station on 053-9242580, the Garda Confidential Line 1800-666111 or any garda station.